Issued  December  16, 1910. 

U.  S.  DEPARTMENT  OF  AGRICULTURE. 

BUREAU  OF  SOILS— MILTON  WHITNEY,  Chief. 

IN  COOPERATION  WITH  THE  UNIVERSITY  OF  CALIFORNIA,  AGRICULTURAL 

EXPERIMENT  STATION,  THOMAS  F.  HUNT,  DIRECTOR;  CHARLES  F. 

SHAW,  IN  CHARGE  SOIL  SURVEY. 


SOIL  SURVEY  GF  THE  UKIAH  AREA, 
CALIFORNIA. 


BY 


E.  B.  WATSON,  OF  the  U.  S.  Department  of  Agriculture,  in 

Charge,  and  R.  L.  PENDLETON,  of  the  University 

OF  California. 


MACY  H.  LAPHAAI,  Inspector,  Western  Di\asiON. 


[Advance  Sheets — Field  Operations  of  tlie  Bareau  of  Soils,  1914.] 


■,logy-Geopnysics  Library. 

:7  Geology 

r-ity  of  California 
"  ^-,    CA  90024 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE 

1916. 


BUREAU  OF  SOILS. 


Milton  "Whitney,  Chief  of  Bureau, 
Albert  G.  Rice,  Chief  Cleric. 

SOIL  SURVEY. 

Curtis  F.  Marrut,  In  Charge. 
G.  W.  Baumann,  Executive* Assistant. 

COMMITTEE   ON    THE   CORRELATION   AND   CLASSIFICATION    OF   SOILS. 

Curtis  F.  Marbut,  Chairman. 
Hugh  H.  Bennett,  Inspector,  Southern  Division. 
W.  Edward  Hearn,  Inspector,  Soutliern  Division. 
Thomas  D.  Rice,  Inspector,  Northern  Division. 
W.  E.  McLendon,  Inspector,  Northern  Division. 
Macy  H.  Lapham,  Inspector,  Western  Division, 

J.  W.  McKericheb,  Secretary, 


Issued  December  16,  1916. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  SOILS— MILTON  WHITNEY,  Chief. 

IN  COOPERATION  WITH  THE  UNIVERSITY  OF  CALIFORNIA,  AGRICULTURAL 

EXPERIMENT  STATION,  THOMAS  F.  HUNT,  DIRECTOR;  CHARLES  F. 

SHAW,  IN  CHARGE  SOIL  SURVEY. 


SOIL  SURVEY  OF  THE  URIAH  AREA, 
CALIFORNIA. 


BY 


E.  B.  WATSON,  OF  the  U.  S.  Department  of  Agriculture,  in 

Charge,  and  R.  L.  PENDLETON,  of  the  University 

OF  California. 


MACY  H.  LAPHAM,  Inspector,  Western  Division. 


[Advance  Sheets— Field  Operations  of  tlie  Bureau  of  Soils,  1914.] 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1916. 


LETTER  OF  TRANSMIHAL 


U.  S.  Department  or  Agriculture,  j 

Bureau  or  Soils,  i 

Washington^  D.  6'.,  Ap^il  IJf,  1916.  i 

Sir  :  In  the  extension  of  the  soil  survey  in  the  State  of  California 

during  the  field  season  of  1914  a  survey  was  made  of  the  Ukiah  area. 

This  work  was  done  in  cooperation  with  the  University  of  California 

Agricultural  Experiment  Station,  and  the  selection  of  the  area  was 

made  after  conference  with  State  officials, 

I  have  the  honor  to  transmit  herewith  the  manuscript  report  and 
map  covering  this  area  and  to  recommend  their  publication  as  ad- 
vance sheets  of  Field  Operations  of  the  Bureau  of  Soils  for  1914, 
as  provided  by  law. 
Respectfully, 

Miltgn  Whitney, 

Chief  of  Bureau. 
Hon.  D.  F.  Houston, 

Secretary  of  Agriculture. 

a 


CONTENTS. 


Page. 
Soil  Survey  of  the  Uriah  Akea,  California.    By  E.  B.  Watson,  of  the 
U.  S.  Department  of  Agriculture,  in  Charge,  and  R.  L.  Pendleton,  of 

THE  University  op  California 5 

Description  of  the  area 5 

Climate 12 

Agriculture 1  14 

Soils 20 

Residual  soils 24 

Mariposa  series 24 

Mariposa  loam 25 

Aiken  series 26 

Aiken  stony  loam 26 

Aiken  loam ■. 27 

Olympic  series 28 

Olympic  stony  loam 29 

Olympic  loam 29 

Climax  series * 30 

Climax  clay  adobe 30 

Miscellaneous 31 

Rough  mountainous  land 31 

Soils  derived  from  old  valley-filling  material 32 

Corning  series 32 

Corning  loam 32 

Corning  gravelly  loam 33 

Corning  gravelly  clay  loam 34 

Pleasanton  series 35 

Pleasanton  gravelly  loam 35 

Pinole  series 36 

Pinole  sandy  loam 36 

Pinole  loam 37 

Pinole  gravelly  loam 38 

Soils  derived  from  recent  alluvial  deposits 39 

Yolo  series 39 

Yolo  fine  sandy  loam,  stream-bottom  phase 40 

Yolo  loam 41 

Yolo  gravelly  loam 42 

Yolo  silt  loam. 44 

Yolo  silty  clay  loam 45 

Tehama  series 46 

Tehama  loam 47 

Tehama  gravelly  loam 47 

Tehama  silt  loam,"  poorly  drained  phase 47 

Honcut  series 48 

Honcut  loam,  red  phase 48 

Honcut  gravelly  loam,  red  phase 49 

Dublin  series 49 

Dublin  clay 50 

Miscellaneous  material 51 

Riverwash l 51 

Summary 51 

3 


ILLUSTRATIONS. 


PLATES. 

Page. 

Plate  I.  View  of  Potter  Valley,  looking  south 16 

II.  Fig.  1. — View  over  Coyote  Valley,  looking  south.  Fig.  2. — Rougli 
mountainous  land,  showing  characteristic  topography 
and  forest  cover 16 

III.  Fig.  1  — Hops  on  stream  bottom  soils  of  the  Yolo  series.    Fig.2. — 

Dry-wine  grapes  on  Pinole  gravelly  loam 32 

IV.  Fig.  1. — Section  in  material  of  Corning  gravelly  clay  loam.     Fig.  2. — 

.   Peach  orchard  on  Corning  gravelly  clay  loam 32 

V.  Fig.  1. — Section  in  old  valley-611ing  material  of  Pinole  gravelly 
loam.  Fig.  2. — Stream-bottom  soils  of  the  Yolo  series, 
near  Ukiah 32 

FIGURES. 

Fig.  1.  Sketch  map  showing  location  of  the  Ukiah  area,  California .-         5 

2,  Sketch  map  showing  location  of  arable  valleys  in  the  Ukiah  area 6 


MAP. 

Soil  map,  Ukiah  sheet,  California. 


4 


SOIL  SURVEY  OF  THH  UKIAH  AREA,  CALIFORNIA. 


By    E.    B.    WATSON,   of   the    U.    S.    Department    of   Agriculture,    in    Charge,    and 
R.  L.  PENDLETON,  of  the  University  of  California. 

DESCRIPTION  OF  THE  AREA. 

The  Ukiah  area  embraces  the  arable  valleys  of  the  Russian  River 
drainage  system  in  Mendocino  County,  Cal.,  together  with  a  portion 
of  the  Coast  Range  Mountains  adjacent  thereto.  It  comprises  an 
area  of  303  square  miles,  or  193,920  acres,  in  the  southeastern  part 
of  Mendocino  County,  and  extends  from  the  southern  boundary  of 
the  county  northward  to  the  limits  of  the  agricultural  land  in  the 
Russian  River  drainage  basin.  The  area  is  about  3(j  miles  long  and 
from  7  to  12  miles  wide. 

The  base  map  used  in  plotting  the  soils  was  constructed  by  plane- 
table  traverse  by  the  field  party,  no  pub- 
lished map  suitable  for  the  purpose  being 
available. 

The  Coast  Ranges  of  northern  Cali- 
fornia occupy  a  belt  50  to  70  miles  wide, 
extending  from  the  coast  eastward  to  the 
Sacramento  Valley.  This  region  is  com- 
posed of  a  series  of  roughly  parallel  ridges 
and  valleys,  or  basins,  wliich  in  the  south- 
em  part  of  Mendocino  County  have  a  trend 
nearly  parallel  to  the  coast.  One  of  these 
large  valley  basins  is  drained  by  the  upper 
part  of  the  Russian  River  and  constitutes 
the  principal  part  of  the  survey.  Within 
this  basin  are  located  several  arable  regions  separated  by  rougher 
hilly  areas.  Each  of  the  arable  areas  has  a  distinctive  name.  As 
an  aid  to  a  clear  understanding  of  their  location  and  relationship, 
the  sketch  map  (fig.  2)  is  given.  This  shows  the  different  arable 
valleys  within  the  survey,  including  the  large  valley  or  basin,  which 
was  partly  or  completely  filled  at  an  early  date  and  out  of  which  the 
Redwood,  Calpella,  Coyotte,  and  Ukiah  Valleys  subsequently  were 
formed.  About  5  miles  east  of  the  northern  part  of  this  main  trough 
or  basin  is  a  short  and  broad  depression,  Potter  Valley,  the  drainage 
of  which  crosses  the  intervening  rtdge  and  unites  with  the  main 
Russian  River  drainage.    This  valley  is  included  in  the  survey  and  is 

5 


Fig.  1. — Sketch  map  showing 
location  of  the  Ukiah  area, 
California. 


FIELD   OPERATIONS   OF    THE   BUREAU    OF   SOILS,  1914. 


Pio.  2. Sketch  map  showing  location  of  arable  valleys  in  the  Ukiah  area. 


SOIL   SURVEY   OF   THE   URIAH   AEEA,   CALIFORNIA.  7 

indicated  on  the  sketch  map.  These  are  the  areas  usually  known  as 
the  upper  Russian  River  valleys,  and  outside  of  these  comparatively 
level  areas  and  three  small  valleys  in  the  southern  part  of  the  area, 
the  drainage  basin  of  the  Russian  River  is  untillable. 

The  elevation  of  the  floors  of  the  several  valleys  varies  from  about 
475  feet  at  the  lower  end  of  Sanel  Valley  in  the  southern  part  of  the 
survey  to  870  feet  in  the  Laughlin  Flat  in  Redwood  Valley,  and  to 
about  1,000  feet  in  the  upper  part  of  Potter  Valley. 

The  gradient  of  the  Russian  River  varies  considerably  in  different 
parts  of  its  course.  Calculations  made  from  the  profile  of  the  North- 
western Pacific  Railroad  indicate  that  the  gradient  through  the  gorge 
at  the  lower  end  of  the  area  surveyed  is  about  15  feet  per  mile.  Just 
above  this,  or  from  the  lower  end  of  Sanel  Valley  up  to  Calpella,  at 
the  junction  of  Forsythe  Creek  and  the  Russian  River,  the  gradient 
varies  from  7  to  10  feet  per  mile.  The  gradient  of  the  East  Fork  of 
Russian  River  through  Potter  Valley  is  comparatively  low,  but  that 
through  the  gorge  leading  from  the  valley  probably  is  twice  as  great 
as  in  the  valley. 

The  arable  valleys  are  mainly  from  1  mile  to  3  miles  wide.  They 
are  not  continuous,  but  are  separated  by  intervening  hills  and  ridges, 
which  are  traversed  in  places  by  narrow  connecting  stream  gorges. 

From  these  nearly  level  valley  floors  the  hills  rise  rather  abruptly 
to  elevations  of  1,500  to  2,500  feet  above  them,  or  from  2,000  to  3,000 
feet  above  sea  level.  Mount  Sanhedrin,  6,200  feet  high,  about  10 
miles  northeast  of  Potter  Valley,  is  the  highest  mountain  in  the  re- 
gion. Duncan  Peak,  which  is  a  conspicuous  feature  of  the  landscape 
near  Hopland,  is  2,700  feet  high.  The  watersheds  on  both  sides  of 
the  drainage  basin  are  about  2,500  to  3,000  feet  high,  with  passes 
through  them  about  1,000  feet  lower  than  the  summits.  These  hills 
for  the  most  part  are  rounded,  and  the  native  vegetation  varies  from 
grass  with  scattered  trees  to  a  heavy  covering  of  chaparral  and  a 
thick  growth  of  trees  on  sheltered  slopes.  Springs  abound  in  the 
hills.  Some  of  these  carry  lime  in  solution  and  have  made  small 
deposits  of  travertine  or  of  impure  limestone;  others  contain  iron 
and  other  minerals,  and  some  are  hot.  Many  of  the  springs  are  re- 
puted to  be  medicinal,  and  health  resorts  have  developed  about  them. 

The  drainage  of  the  entire  area  is  carried  by  the  Russian  River, 
which  flows  southward  through  the  center  of  the  area,  with  important 
tributaries  from  both  the  east  and  west.  The  drainage  of  the 
hills  is  very  well  established,  and  drainage  channels  of  relatively 
high  gradients  reach  into  every  part  of  the  hilly  areas.  The  drainage 
of  the  vallej^  floors  is  generally  complete,  but  there  are  a  few  places 
where  it  is  imperfect.  The  streams  of  the  region  are  mainly  perennial 
in  the  sections  underlain  by  consolidated  rocks,  but  in  the  alluvial 
valleys  during  the  summer  they  sink  into  the  gravels  and  disappear. 


8  FIELD   OPERATIONS   OF    THE   BUEEATJ   OF   SOILS,  1914. 

The  several  arable  valleys  differ  from  each  other  in  their  physical 
characteristics.  Avhich  have  influenced  their  settlement  and  develop- 
ment, SO  that  they  can  best  be  described  separately. 

Potter  Y alley. — Potter  Valley  lies  in  the  extreme  northeastern  part 
of  the  TJkiah  area  and  is  drained  by  the  East  Fork  of  the  Russian 
River.  No  very  large  streams  enter  it.  The  valley  is  about  7  miles 
long  and  2  miles  wide.  It  is  characterized  by  a  broad,  level  floor, 
which  seems  to  be  a  recently  drained  basin,  merging  into  low  alluvial 
fans  having  a  gentle  slope  up  to  the  surrounding  hills  (PI.  I).  A 
part  of  the  floor  of  the  valley  has  until  recently  been  poorly  drained, 
and  the  effect  of  this  condition  is  seen  in  the  character  of  the  soil. 
Remnants  of  old  valley-filling  material,  rising  from  5  to  20  feet 
above  the  floor  of  the  valley,  occur  in  a  nvnnber  of  places  in  the 
southern  half  of  the  valley,  and  remnants  of  a  -still  older  valley 
filling,  from  100  to  400  feet  high,  border  the  valley  on  the  west, 
but  there  are  no  such  remnants  on  the  east.  In  the  southeastern 
extremity  of  the  valley,  however,  where  Mewhinney  Creek  enters, 
there  are  high  remnants  of  old  valley  filling. 

The  first  settlers  found  the  valley  parklike,  with  an  open  cover, 
including  scattered  trees  of  valley  oak  and  small  groves  of  various 
trees  covering  perhaps  one-third  of  the  area.  They  could  plow 
many  fields  without  the  trouble  of  clearing.  Although  the  soils 
are  productive,  markets  have  been  more  or  less  inaccessible,  and  as 
a  result  stock  raising  became  the  chief  form  of  agriculture.  The 
stock  ranged  in  the  hills  and  in  the  stubble  fields  after  harvest,  the 
hay  and  grain  produced  being  used  to  fatten  the  animals  for  market. 
This  type  of  farming  has  continued  to  the  present  time. 

The  cause  of  the  thin  covering  of  trees  in  Potter  Valley,  while 
Redwood  Valley  just  across  the  ridge  to  the  west  was  densely  wooded, 
is  a  matter  of  interest.  The  most  probable  explanation  is  that  there 
is  less  rainfall  than  in  Redwood  Valley.  It  is  shown  in  the  discus- 
sion of  climate  that  there  are  variations  in  the  rainfall  in  different 
parts  of  the  area,  and  the  fact  that  Redwood  Valley  is  about  6  miles 
nearer  the  coast  and  has  a  pronounced  gap  in  its  western  wall 
(Forsythe  Creek  Valley)  through  which  the  ocean  winds  may  blow, 
while  Potter  Valley  has  a  relatively  high  ridge  to  the  west  of  it. 
probably  accounts  for  the  difference  in  precipitation.  The  more 
open  cover  was,  no  doubt,  one  of  W\^  main  reasons  for  this  valley 
being  settled  much  sooner  and  more  completely  than  RedAvood 
Valley.  The  large  proportion  of  recent  alluvial  soils  and  the  dis- 
tance from  markets  have  been  important  factors  in  determining"  the 
type  of  agriculture  followed. 

Redwood  Valley. — Redwood  Valley  is  the  most  northern  of  the 
valleys  drained  by  the  central  fork  of  the  Russian  River.  It  is 
roughly  triangular  in  shape,  about  4  miles  wide  and  5  miles  long, 


SOIL   SURVEY   OF   THE    URIAH   AKEA,   CALIFORNIA.  9 

with  its  base  lying  to  the  south  and  the  apex  to  the  north,  where 
the  Russian  River  enters  the  valley.  Forsythe  Creek,  which  enters 
from  the  west,  carries  much  more  water  than  the  central  stream. 
Redwood  Valley  is  characterized  by  a  narrow  river  flood  plain  and 
a  broad  expanse  of  old  alluvial  valley  filling  or  river  terrace  from 
10  to  75  feet  above  the  flood  plain.  It  is  bounded  on  the  south 
and  southeast  by  high  hills  of  old  unconsolidated  valley-filling  ma- 
terial from  400  to  600  feet  high.  There  are  no  high  areas  of  old 
valley-filling  materials  at  the  north  end  of  tha  valley. 

The  greater  part  of  Redwood  Valley  originally  was  heavily 
forested  with  a  growth  of  oak,  fir.  and  manzanita.  Apparently  there 
was  some  open  country  in  the  northern  part.  The  dense  growth 
of  timber  retarded  settlement.  The  bottoms  were  found  to  be  very 
productive  and  were  cleared  at  an  early  date.  The  bench  lands 
constituting  most  of  the  valley  were  not  so  well  suited  to  grain  pro- 
duction, the  only  type  of  farming  attempted.  The  belief  became 
fixed  that  the  bench  lands  were  poor,  and  the  dense  covering  made 
the  cost  of  clearing  high.  These  factors  have  materially  modified  the 
development  of  this  valley,  as  compared  with  that  of  Potter  Valley 
and  Ukiah  Valley.  These  valleys  were  settled  about  the  same  time, 
but  at  present  Potter  Valley  and  Ukiah  Valley  are  almost  entirely 
cleared  and  farmed,  while  a  large  part  of  Redwood  Valley  is  forested. 
Interest  in  the  possibilities  of  growing  fruit  on  the  bench  lands  is 
now  being  manifested.  There  are  no  commercial  orchards  of  bear- 
ing age  in  the  valley,  but  home  orchards  indicate  the  suitability  of 
the  land  for  fruit  production. 

Cold  Creek  Valley. — Cold  Creek  Valley  is  small  and  not  very  im- 
portant agi'iculturally.  It  is  located  a  few  miles  south  of  Potter 
Valley.  Cold  Creek  is  a  tributary  of  the  East  Fork  of  the  Russian 
River.  The  part  of  Cold  Creek  Valley  included  in  this  area  is  about 
one-eighth  mile  wide  and  4  miles  long.  The  valley  extends  beyond  the 
area  surveyed. 

The  valley  of  Cold  Creek  is  interesting  because  it  evidently  belongs 
to  a  middle-aged  stream  which  is  a  tributary  to  a  very  youthful 
stream.  The  East  Fork  of  the  Russian  River  flows  with  a  high  gra- 
dient through  a  V-shaped  gorge.  It  has  a  youthful  topography.  Cold 
Creek,  a  tributary,  flows  at  a  much  lower  gradient,  as  is  evidenced  by 
the  size  of  the  stones  in  its  bed.  and  has  a  distinct  flood  plain  and  also 
a  terrace.    It  has  attained  middle  age. 

Holway^  has  established  the  fact  that  Cold  Creek  has  lost  a  large 
tributary,  Scott  Creek,  by  a  large  landslide  which  diverted  the  waters 
to  Clear  Lake  and  thence  to  the  Sacramento  River.  This  probably 
has  a  bearing  on  the  anomalous  condition  just  noted. 

1  Holway,  "  The  Russian  River,"  Univ.  of  Cal.  Pub.  in  Geog.,  vol.  1,  Ko.  1.     . 
42235°— 16 2 


10  FIELD   OPERATIONS   OP   THE   BUREAU   OF   SOILS,   1914. 

Cdlpella  Valley. — Calpella  Valley  lies  between  the  two  large  rem- 
nants of  old  valley  filling  just  south  of  Redwood  Valley.  This  is  a 
small  valley,  barely  one-half  mile  wide,  and  2  miles  long.  It  com- 
prises a  very  narrow  flood  plain,  and  above  this  a  series  of  terraces 
which  blend  into  each  other  and  are  bounded  on  both  the  east  and 
the  west  by  the  high  eroded  early  valley  filling. 

Although  this  valley  was  settled  at  an  early  date  and  was  on  the 
main  thoroughfare  for  travel  north  and  south,  much  of  it  is  un- 
cleared and  undeveloped.  It  has  had  about  the  same  agricultural 
history  as  Redwood  Valley. 

Coyote  Valley. — This  valley  lies  east  of  Calpella  Valley  across  a 
high  ridge  of  early  alluvial-fan  or  old  valley-filling  material  (PL  II, 
fig.  1).  It  evidently  is  a  recent  valley  carved  out  of  the  old  valley- 
filling  deposits  by  the  East  Fork  of  the  Russian  River,  which  flows 
through  it.  It  is  hardly  1  mide  wide  and  is  2^  miles  long.  The  soils 
occupy  mainly  a  low  terrace,  modified  in  places  by  recent  fan  de- 
posits, and  are  quite  productive. 

JJkiah  Valley. — The  Ukiah  Valley  is  the  most  important  of  the 
arable  valleys  in  the  area.  It  lies  south  of  Calpella  and  Coyote  Val- 
leys, near  the  center  of  the  area  surveyed.  It  is  from  2  to  4  miles 
wide  and  about  10  miles  long.  The  Russian  River  flows  through 
its  entire  length,  and  several  fairly  large  streams  enter  from  both 
sides.  It  is  characterized  by  a  wide  flood  plain  of  the  Russian 
River,  by  low,  fertile  recent  alluvial  fans,  formed  by  several  of  the 
smaller  lateral  streams,  and  by  low  bench  lands  bordeiing  the  present 
flood  plains  and  having  a  topography  well  suited  to  cultivation.  This 
valley  is  intermediate  in  physiographic  features  between  Potter 
Valley  and  Redwood  Valley.  Its  forest  covering  was  also  probably 
intermediate  in  density. 

Its  productive  soils,  found  in  large  bodies,  and  its  location  are  fac- 
tors which  have  encouraged  development.  Along  Robertson  Creek, 
which  enters  the  southern  part  of  the  valley  from  the  west,  there  is  a 
small  extension,  the  characteristics  of  w^hich  are  much  the  same  as 
ihose  of  the  main  valley. 

Knights  Valley. — Knights  Valley  is  south  of  Ukiah  Valley,  and  is 
separated  from  it  by  a  low  ridge  covered  by  residual  soils.  This  is  a 
small  valley  with  its  axis  lying  oblique  to  that  of  the  main  valleys. 
It  is  about  3  miles  long  in  its  greatest  extension,  very  narrow  at  its 
upper  end,  and  1^  miles  wide  at  its  lower  end. 

The  drainage  of  this  valley  is  carried  by  MciSTab  Creek,  which 
unites  with  the  Russian  River  about  a  mile  below  the  valley.  The 
upper  or  western  extension  of  the  valle}^  has  a  good  slope,  but 
the  lower  part  is  basinlike.  The  topography  in  this  part  is  level 
and  the  soils  are  heavy,  indicating  deposition  from  quiet  waters. 


SOIL   SURVEY   OF    THE   URIAH   AREA,   CALIFORNIA.  11 

Sanel  Valley. — South  of  Knights  Valley  is  the  Sanel  Valley, 
which  is  quite  irregular  in  outline.  It  is  about  5  miles  long  and  1 
mile  wide,  with  a  small  side  valley  at  the  northern  end  extending 
westward  from  Largo,  a  larger  side  valley  at  the  southern  end 
extending  westward,  and  a  large  extension  on  the  east  side. 
This  valley  is  characterized  by  a  wide  flood  plain  and  relatively 
small  alluvial  fans  and  a  relatively  large  deposit  of  old  valley  filling 
in  the  southern  part.  The  soils  are  very  productive,  and  the  large 
area  of  smooth  flood  plains  has  encouraged  its  development. 

McDowell  Valley. — McDowell  Valley  is  a  small  valley  lying  east 
of  Sanel  Valley  across  a  narrow  ridge.  This  valley  is  about  2^ 
miles  long  and  1  mile  wide.  It  is  narrower  at  the  north,  widening 
out  somewhat  toward  the  south.  McDowell  Creek  carries  its  drain- 
age westward  through  the  narrow  ridge  into  the  Russian  River. 
McDowell  Valley  differs  from  the  other  valleys  in  the  area  in 
having  no  flood  plain  along  the  stream  which  drains  it,  the  valley 
floor  lying  well  above  the  bed  of  the  stream  and  about  on  a  level 
with  the  lowest  part  of  the  inclosing  rim.  Apparently  the  depres- 
sion was  filled  to  the  rim,  and  later  the  stream  cut  down  the  outlet, 
but  it  has  not  yet  succeeded  in  taking  out  any  considerable  amount 
of  the  original  valley  filling.  The  gorge  has  been  eroded  60  to  75 
feet  below  the  valley  floor.  The  valley  apparently  was  largely  for- 
ested originally,  and  considerable  timber  remains  in  places.  A  large 
part  has  been  cleared.  The  soil  is  fairl}^  productive,  comparing  very 
favorably  with  the  bench  land  of  Ukiah  and  Redwood  Valleys. 

There  is  one  very  small  valley,  not  indicated  on  the  sketch  map, 
on  a  side  stream  which  enters  the  gorge  of  the  Russian  River  at 
Echo.  The  soils  of  this  valley  are  derived  from  flood-plain  and 
low  alluvial-fan  materials  and  are  very  productive. 

Before  the  advent  of  the  white  man  the  Ukiah  area  was  inhabited 
by  the  Pomo  Indians.  These  were  peaceful,  domestic  Indians,  who 
derived  their  living  from  hunting,  fishing,  and  gathering  acorns  and 
wild  fruits.  Apparently  very  little  of  the  land  was  cultivated.  Be- 
tween 1850  and  1855  a  few  settlers  located  in  Ukiah  Valley  and 
Potter  Valley.  From  1855  to  1860  settlement  was  quite  rapid,  and 
Mendocino  County  was  organized  in  1859,  with  Ukiah  as  the  county 
seat.  The  centers  of  settlement  were  Sanel  Valley,  Ukiah  Valley, 
and  Potter  Valley,  which  seem  to  have  been  settled  and  developed 
at  the  same  time.  Since  about  1860  the  development  of  the  region 
has  been  gradual. 

About  75  per  cent  of  the  early  settlers  came  from  Southern  and 
Central  States,  and  the  remainder  from  other  parts  of  the  United 
States  and  from  foreign  countries.  The  Indians  have  decreased  in 
number  until  only  a  few^  small  settlements  remain,  scattered  through- 
out the  area.     The  white  population  has  continued  predominantly 


12  FIELD   OPERATIONS   OF    THE   BUEEAU   OF   SOILS,  1914. 

Anglo-Saxon.  A  few  Italians  and  Swiss  have  settled  in  the  region 
in  the  last  10  j^ears  and  are  engaged  mainly  in  grape  growing.  There 
are  but  few  Chinese  and  Japanese,  and  they  are  mainly  laborers. 
The  rural  population  is  principally  confined  to  the  level  valleys. 
The  population  of  the  foothills  is  very  sparse.  The  three  political 
townships  of  Potter  Valley,  Ukiah,  and  Sanel  were  given  a  popu- 
lation of  6,587  in  the  last  census.  These  townships  are  nearly  identi- 
cal with  the  area  surveyed. 

The  area  is  traversed  by  the  Northwestern  Pacific  Railroad,  which 
follows  approximately  the  course  of  the  Russian  River  from  the 
southern  boundary  of  the  area  to  Redwood  Valley  Station,  in  the 
northern  part.  Here  it  turns  to  the  northwest,  and  crosses  the  divide 
to  Willits  and  Eureka.  To  the  south  this  railroad  gives  connections 
with  San  Francisco. 

A  State  highway  is  being  built  approximately  parallel  to  the  rail- 
road, and  is  nearing  completion.  This  has  a  solid  roadbed  of  easy 
grade,  making  travel  easy  at  all  times  of  the  year.  In  addition,  there 
is  a  good  system  of  roads  reaching  all  the  agricultural  areas,  and 
means  of  communication  are  as  good  as  the  nature  of  the  country 
will  permit. 

Ukiah  is  the  principal  town  in  the  area.  It  is  situated  on  the  rail- 
load  in  the  Ukiah  Valley.  Its  population  is  reported  in  the  1910 
census  as  2,136.  Ukiah  is  the  business  center  of  the  valley  and  the 
shipping  point  for  the  ranches  back  in  the  hills  for  many  miles.  A 
number  of  stages  operate  betM^een  this  point  and  various  towns  and 
pleasure  resorts  in  the  Coast  Range.  The  small  town  of  Potter 
Valley  is  the  trading  center  of  the  valley  of  the  same  name.  There  is 
no  railroad  in  this  valley.  Calpella  is  a  small  town  in  the  Calpella 
Valley.  Ilopland  is  located  near  the  center  of  Sanel  Valley  on  the 
railroad.  It  has  grown  up  since  the  railroad  was  constructed.  Old 
Hopland,  1  mile  to  the  east  across  the  river,  was  the  business  center 
of  the  valley  during  the  days  of  the  toll  roacls.  Hopland  has  a  popu- 
lation of  about  200  people,  and  Old  Hopland  about  100.  Echo,  Cum- 
miskey,  Pieta,  Fountain,  Largo,  Henry,  El  Roble,  Redwood  Valley, 
and  Laughlin  are  shipping  points  on  the  railroad. 

All  the  grain  and  hay  produced  are  sold  within  the  area.  The 
live  stock,  hops,  and  fruit  are  mainly  shipped  south  to  the  bay 
region,  but  some  is  sold  in  the  lumbering  towns  to  the  north. 

CLIMATE. 

The  climate  of  the  Ukiah  area  resembles  that  of  the  Great  Interior 
Valley  of  California  in  that  it  has  a  rainy  season  of  moderate  tem- 
perature and  a  dry  season  with  high  temperatures,  but  it  differs  in 
that  the  rainfall  is  greater  and  the  temperature  range  is  less.     It  is 


SOIL   SURVEY   OP   THE   UKIAH   AREA,   CALIFORNIA.  13 

intermediate  in  climate  as  well  as  in  position  between  the  Interior 
Valley  and  the  coast  region  of  Mendocino  County,  which  has  a  still 
greater  rainfall  and  cooler  simimers.  Its  climate  is  very  similar  to 
that  of  the  neighboring  valleys  in  the  Coast  Eange. 

The  rainy  season  occurs  in  the  winter  months,  from  the  first  of 
November  to  the  last  of  April.  The  five  months  from  May  to 
September,  inclusive,  constitute  the  summer  or  dry  season.  The 
mean  annual  precipitation  at  Ukiah,  the  only  place  in  the  area  at 
which  official  Weather  Bureau  records  are  kept,  is  37.3  inches.  Of 
this  amount  2,2  inches  falls  in  the  five  months  of  the  dry  season. 

The  mean  annual  temperature  is  57.6°  F.,  which  is  practically  the 
same  as  that  at  Santa  Rosa,  55  miles  to  the  south.  It  averaj^es  dur- 
ing the  rainy  season  about  49°,  or  nearly  3°  colder  than  at  Santa 
Rosa.  From  May  to  October,  inclusive,  it  averages  about  66",  or 
nearly  2°  warmer  than  at  Santa  Rosa.  This  apparently  is  due  to 
the  fact  that  this  valley  is  not  so  open  toward  the  sea  as  Santa  Rosa 
Valley. 

The  average  date  of  the  first  killing  frost  in  the  fall  is  Novem- 
ber 1,  and  of  the  last  in  the  spring  April  14.  The  earliest  recorded 
date  of  killing  frost  in  the  fall  is  October  16,  and  the  latest  date  in 
the  spring  May  2.    There  is  a  normal  growing  season  of  201  days. 

There  are  very  few  days  when  the  temperature  goes  above  100°, 
and  the  hot  spells  are  of  short  duration.  Snow  very  seldom  falls, 
and  lasts  but  a  few  hours. 

The  great  variation  in  the  width  of  the  valley,  its  elevation,  and 
relation  to  gaps  in  the  hills  through  which  the  winds  come,  makes 
variations  in  precipitation,  temperature,  and  winds  in  different 
parts  of  the  area  seem  very  probable,  but  actual  data  on  this  subject 
are  scarce.  A  record  of  the  rainfall  at  the  power  plant  at  the  head 
of  Potter  Valley  for  three  seasons,  compared  with  the  rainfall  at 
Ukiah  for  the  corresponding  seasons,  shows  10.7  inches  less  rainfall 
in  Potter  Valley.  It  seems  probable  that  certain  parts  of  the  area 
have  a  greater  rainfall  than  Ukiah,  so  that  the  extreme  variations 
between  different  parts  of  the  area  is  probably  much  greater  than  10 
inches.  The  variations  in  temperature,  frosts,  and  winds  also  prob- 
ably is  considerable.  This  matter  of  local  variation  in  climate  must 
be  taken  into  consideration  in  fruit  growing  in  different  parts  of  the 
area,  but  definite  information  on  this  point  can  not  be  given  owing 
to  the  lack  of  data. 

On  the  whole  the  climate  is  well  suited  to  the  production  of  gen- 
eral farm  crops,  alfalfa,  hops,  grapes,  and  most  tree  and  bush  fruits. 
It  is  not  well  suited  to  citrus  fruits ;  there  are  some  areas  in  the  hills, 
from  500  to  1,000  feet  above  the  valley  floors,  where  oranges  can  be 
grown,  but  the  area  of  suitable  soil  in  these  localities  is  very  small. 


14 


FIELD   OPERATIONS   OF    THE   BUREAU   OF   SOILS,   1914. 


Relatively  few  fogs  occur,  and  these  generally  disappear  early  in 
the  day.  High  winds  are  very  rare.  The  coast  breeze  during  the 
summer  season  reaches  the  valleys  through  several  gaps,  notably  in 
Redwood  Valley  through  Forsythe  Creek  gap. 

The  accompanying  table,  giving  the  normal  monthly,  seasonal, 
and  annual  temperature  and  precipitation,  is  compiled  from  the  rec- 
ords of  the  Weather  Bureau  station  at  Ukiah : 


Noniial  mouthly,  seasonal,  and  annual  temperature  and  precipitation  at  XJkiah. 


Temperature. 

Precipitation. 

Month. 

Mean. 

Absolute 
maximum. 

Absolute 
minimum. 

Mean. 

Total 

amount  for 

the  driest 

year. 

Total 
amount  for 
the  wettes; 

year. 

'F. 
44.7 
45.1 
47.7 

°F. 

86 
77 
82 

'F. 
20 
12 
18 

Inches. 
6.65 
8.35 
6.17 

Jnchea. 
2.41 
1.23 

7.  OS 

Inches. 
5.81 

30.75 

12.53 

Winter 

45.8 

86 

12 

21.17 

10.72 

49.09 

March 

50.2 
55.0 
60.4 

85 
92 
102 

24 
27 
30 

5.55 
2.45 
1.26 

0.68 
0.80 
1.63 

4.56 

0.00 

May..    .               

0.00 

Spring 

55.2 

102 

24 

9.26 

1 

3.11 

4.56 

June 

67.7 
73.4 
71.8 

107 
112 
114 

36 
39 
40 

0.34 
0.02 
0.01 

0.65 
0.00 
Trace. 

0.10 

Julv 

0.04 

August.          

0.00 

71.0 

114 

36 

0.37 

0.65 

0.14 

September 

65.7 
58.4 
51.2 

108 
98 
80 

32 
26 
22 

0.57 
1.78 
4.15 

0.82 
1.24 
2.02 

0.48 

October 

2.36 

November 

5.14 

Fall      

58.4 

108 

22 

6.50 

4.08 

7.98 

Year 

57.6 

114 

12 

37.30 

18.56 

61.77 

AGRICULTURE. 

Cultivation  of  the  soil  began  with  the  first  settlement  of  the  area, 
between  1850  and  1860,  and  it  is  probable  that  the  better  alluvial 
soils  were  cleared  during  or  soon  after  this  period.  Stock  raising 
was  the  principal  industry  from  the  first,  and  the  hay  and  most  of 
the  grain  produced  on  the  cultivated  area  was  used  for  feed  for  the 
stock.  It  was  so  far  to  market  that  little  besides  stock  could  be 
taken  out.  Family  orchards  w^ere  set  out  and  as  a  rule  did  very 
well.  Wheat  was  milled  for  home  consumption.  In  1889  the  North- 
western Pacific  Railroad  was  completed  to  Ukiah,  and  this  gave 
access  to  markets,  but  the  farmers  have  been  very  slow  to  change 
their  established  system  of  agriculture,  especially  in  the  northern 


SOIL   SURVEY    OF   THE   UKIAH   AREA,   CALIFORNIA.  15 

part  of  the  area.  Soon  after  the  advent  of  the  railroad  a  few  com- 
mercial orchards  of  pears  and  prunes  were  set  out.  These  have  been 
profitable.  There  is  very  much  less  fruit  grown  in  this  area  than 
in  the  part  of  the  Russian  River  Valley  to  the  south  within  the 
adjoining  county  of  Sonoma.  This  is  due  not  to  differences  in  soil 
or  climate,  but  to  the  later  development  of  transportation  facilities 
and  to  the  conservative  character  of  the  people.  Fruit  growing 
seems  destined  to  be  an  important  industry  in  the  area,  notwithstand- 
ing the  fact  that  its  extension  northward  has  been  slow. 

The  growing  of  hops  began  in  the  seventies  and  was  a  well-estab- 
lished industry  by  1877.  The  soils  of  the  alluvial  stream  bottoms 
were  found  particularly  adapted  to  hops,  but  the  industry  developed 
irregularly,  owing  to  the  fluctuations  in  the  market  value  of  the 
crop.  At  present  it  is  one  of  the  largest  industries  of  the  area. 
Tobacco  was  grown  in  a  small  way  about  1861,  and  it  is  claimed  that 
the  crop  did  well.    At  the  present  time,  however,  it  is  not  grown. 

Grapes  for  making  wine  and  for  table  use  have  been  grown  in  the 
area  probably  since  the  earliest  settlements.  Some  vineyards  contain 
large  vines  30  to  40  years  old.  The  early  development  of  this  in- 
dustry was  slow,  but  about  1900  grape  growing  received  an  impetus 
and  has  expanded  steadily  since  that  time.  It  is  claimed  that  the 
phylloxera  prevalent  in  the  districts  south  of  the  survey  has  not  yet 
passed  the  barrier  of  uncultivated  hill  land  to  the  south,  and  that 
the  vineyards  of  this  area  are  free  from  that  disease.  The  vineyards, 
where  given  proper  care,  have  done  well.  They  have  been  put  out 
mainly  on  the  bench  and  rolling  lands,  as  the  bottom  lands  were  used 
for  hops,  alfalfa,  and  grain.  They  were  introduced  not  to  replace 
other  crops,  but  to  supplement  them  by  being  planted  on  soils  not 
so  well  suited  to  these  other  crops. 

It  is  impossible  to  give  statistics  in  regard  to  live  stock  or  crops 
in  the  area  for  the  reason  that  the  area  is  only  a  part  of  the  county 
and  all  figures  available  are  for  the  county  as  a  whole.  The  in- 
formation given  in  the  following  pages  in  regard  to  agriculture  in 
the  area  at  the  present  time  is  mainly  the  result  of  observations  in 
the  field,  supplemented  wherever  possible  by  published  statistics. 

The  principal  kinds  of  live  stock,  named  in  order  of  their  im- 
portance, are  cattle,  sheep,  hogs,  and  horses.  The  rolling  hills  indi- 
cated on  the  accompanying  soil  map  as  Rough  mountainous  land  are 
used  for  ranges  for  cattle  and  sheejo  (see  PI.  II,  fig.  2),  Feed  grown 
on  the  arable  land,  including  hay,  grain-hay,  and  alfalfa,  is  used 
by  some  ranchers  to  carry  the  stock  through  the  periods  of  scanty 
pasturage  and  to  fatten  them;  others  depend  on  the  range  entirely. 
Most  of  the  foothill  soils  seem  best  suited  to  pasture.  The  proportion 
of  arable  land  devoted  to  the  production  of  winter  feed  for  stock  is 
growing  steadily  less,  as  it  is  found  much  more  profitable  to  grow 


16  FIELD  OPERATIONS  OF   THE  BUREAU   OF   SOILS,  1914. 

hops,  grapes,  and  fruit  than  it  is  to  grow  feed,  except  in  the  case  of 
alfalfa.  Few  horses  are  raised,  except  for  farm  use.  Hogs  are  raised 
in  considerable  numbers.  They  are  raised  on  the  range,  but  are  fed 
grain  in  addition.  There  is  a  large  poultry  farm  in  Hopland;  the 
remainder  of  the  poultr}^  in  the  area  is  in  small  farm  flocks. 

Considerable  grain  is  grown,  especially  in  the  northern  part  of 
the  area  and  in  Potter  Valley.  Wheat  is  the  principal  grain  crop, 
closely  followed  by  oats,  with  barley  and  corn  having  a  smaller 
acreage.  However,  not  enough  grain  is  grown  for  home  consump- 
tion, and  flour  and  feed  are  shipped  in.  A  larger  acreage  of  grain- 
hay  is  grown,  and  all  of  this  is  used  for  stock  feed.  The  grain, 
especially  corn,  does  best  on  the  alluvial  soils  consisting  of  the  river 
flood  plains  and  recent  alluvial-fan  soils.  This  is  due  not  only  to 
their  high  productiveness,  but  also  to  the  fact  that  the  supply  of 
moisture  can  be  conserved  by  proper  cultivation  during  the  dry  sea- 
son better  than  on  the  bench  soils.  Grain  is  grown,  on  the  Pleasanton 
and  Pinole  soils,  but  the  yields  are  often  very  light  and  on  the 
average  the  practice  is  not  found  profitable. 

Alfalfa  is  a  new  crop  in  the  area,  but  is  gaining  in  favor  very 
rapidly.  It  does  well  on  soils  of  the  Yolo  series,  where  it  can  be 
grown  profitably  without  irrigation.  In  Potter  Valley  the  crop  is 
grown  on  the  Yolo  soils  occurring  upon  the  alluvial  fans.  The  up- 
land soils,  however,  such  as  those  of  the  Pinole  series,  are  not  so 
well  suited  to  alfalfa,  though  if  abundant  water  could  be  supplied 
for  irrigation  it  seems  probable  that  the  crop  would  do  fairly  well 
on  the  bench  soils.  Irrigation  is  being  tried  on  the  alluvial  soils. 
It  seems  profitable  and  probably  will  be  extended,  the  yields  being 
increased  by  this  means. 

The  Eussian  River  Valley  is  one  of  the  main  hop-growing  centers 
of  California,  Mendocino  and  Sonoma  Counties  together  reporting 
more  than  one-half  the  hops  produced  in  the  State.  This  is  an 
intensive  crop,  requiring  a  large  expenditure  per  acre  in  the  way 
of  equipment  and  labor,  but  giving  under  favorable  conditions  very 
large  returns.  Hops  are  grown  from  root  cuttings.  These  are 
planted  in  hills  about  eight  feet  apart  each  way.  After  the  vines 
begin  to  run  they  are  supplied  with  supports.  Two  systems  are 
followed  in  this  area.  In  one  system  a  permanent  network  of  heavy 
wires  is  stretched  over  the  field,  about  16  feet  above  the  ground. 
Strings  reach  from  tlie  wires  to  the  ground  and  6  vines  from  each 
hill  are  trained  up  these  strings.  This  system  costs  about  $50  an 
acre  to  install.  The  other  system  is  cheaper,  but  it  is  claimed  that 
not  as  good  a  quality  of  hops  is  raised.  Poles  about  7  feet  long 
are  set  in  each  hill,  and  strings  are  stretched  along  the  tops  from 
pole  to  pole,  forming  a  network  over  which  the  vines  spread  in  their 
growth  (PI.  Ill,  fig.  1).  The  owner  usually  cultivates  the  fields, 
but  the  work  of  cultivation  in  the  hill,  pruning,  suckering,  trimming, 


Report  of  Bureau  of  Soils,  U.  S.  Dept.  of  Agriculture,  1914.  PLATE   I. 


Report  of  Bureau  of  Soils,  U.  S.  Dept.  of  Agriculture,  1914. 


Plate  II. 


Fig.  1.— View  Over  Coyote  Valley,  Looking  South, 

Ridge  of  old  vrtlley-filling  niiiterial  defining  the  valley  on  the  right.    Cleared  areas  on  this 
ridge  in  distance  planted  to  vineyards. 


Fig.  2.— Rough  Mountainous  Land,  Showing  Characteristic  Topography  and 

Forest  Cover. 


SOIL   SURVEY    OF    THE   URIAH   AREA,    CALIFORNIA.  17 

stringing,  and  training  is  given  out  by  contract.  This  costs  about  $19 
an  acre  if  the  overhead  trellis  is  used,  and  $25  an  acre  where  the 
small  poles  are  used.  T^Is  work  is  done  mainly  by  Indian  or 
Japanese  labor.  Picking  is  paid  for  by  the  hundred  pounds.  After 
picking  the  hops  are  taken  to  large  drying  kilns,  foimd  on  every 
hop  ranch  of  any  size,  where  they  are  sulphured  and  dried  by  arti- 
ficial heat,  cooled,  baled,  and  stored.  It  is  reported  that  it  costs 
ijbout  9  cents  a  pound  to  grow  hops.  The  business  is  highly  specu- 
lative because  of  the  great  fluctuation  in  price.  Hops  give  a  light 
crop  the  first  year,  come  into  full  bearing  the  second  year,  and  remain 
productive  for  many  years.  Hops  in  this  area  are  grown  almost 
exclusively  on  the  stream-bottom  phases  of  the  Yolo  silt  loam  and 
the  Yolo  fine  sandy  loam.  In  Potter  Valley  a  few  hopyards  are 
found  also  on  the  alluvial-fan  soils  of  the  Yolo  series. 

The  pear  industry  is  not  extensively  developed  in  the  area,  but 
there  are  a  number  of  commercial  orchards  of  fair  size  and  new  ones 
are  being  set  out.  The  Bartlett  is  the  only  variety  grown.  Pears 
from  this  area  bring  top  prices,  as  the  quality  is  excellent.  The 
orchards  are  well  cared  for  and  no  blight  was  seen  at  the  tima 
of  the  survey,  although  it  has  been  troublesome  in  the  past.  The 
fresh  fruit  is  shipped  to  eastern  markets  or  sold  locally  to  the  can- 
neries. The  inferior  fruit  is  dried.  What  is  said  to  be  one  of  the 
most  profitable  pear  orchards  in  California  is  located  on  the  Yolo 
fine  sandy  loam,  stream-bottom  phase,  near  Old  Hopland.  Other 
orchards  are  found  on  the  stream-bottom  phases  of  the  Yolo  silt 
loam  and  the  silty  clay  loam.  Orchards  are  being  set  out  on  the 
Yolo  soils  of  the  alluvial  fans  and  on  the  soils  of  the  Pinole  series. 
It  seems  probable  that  the  Yolo  silt  loam  and  the  Yolo  silty  clay 
loam  of  the  alluvial  fans  will  be  found  good  soils  for  this  crop.  Its 
success  on  the  bench  soils  is  not  so  certain. 

Prunes  are  grown  commercially  in  the  area  and  rank  with  pears  in 
importance.  The  French  Petite  prune  is  grown  almost  exclusively. 
The  orchards  are  found  mainly  on  the  Yolo  alluvial-fan  soils,  with 
some  on  the  stream-bottom  phase  of  the  Yolo  silt  loam,  and  new 
orchards  are  being  set  out  on  practically  all  the  soils  in  the  area. 
The  bearing  orchards  have  been  profitable,  but  the  trees  do  not  seem 
to  have  quite  the  vigor  and  growth  of  trees  in  other  prune  sections 
of  the  State. 

There  are  no  bearing  commercial  orchards  of  peaches  and  apples 
in  the  area,  but  there  are  a  large  number  of  home  orchards  that  in 
the  main  have  done  well.  A  few  commercial  orchards  are  being  set 
out  on  tlie  Pinole  and  other  bench  soils,  and  it  seems  probable  that 
these  soils  are  well  suited  to  the  production  of  both  fruits. 

Grapes  are  more  important  than  any  other  fruit  in  the  area.    They 
are  grown  almost  exclusively  for  wine.     The  vineyards  are  found 
42235°— 16 3 


18  FIELD   OPERATIONS   OF    THE   BUREAU   OF   SOILS,   1914. 

mainly  on  the  higher,  drier,  and  lighter  textured  soils  and  are  located 
largely  on  soils  not  so  well  suited  to  other  crops.  The  Pleasanton 
i>,nd  Pinole  soils  are  particularly  suited  to  grapes  (PI.  Ill,  lig.  -2), 
but  they  do  well  on  practically  all  the  soils  of  the  area.  The  richer 
alluvial  soils,  however,  may  give  greater  returns  in  other  fruits. 
The  residual  Mariposa  loam  does  not  seem  so  well  suited  to  the  grape. 
It  is  reported  that  the  grapes  grown  on  the  upland  soils  of  the  val- 
leys, those  of  the  Pleasanton  and  Pinole  series,  are  of  better  quality 
and  have  a  higher  content  of  sugar  than  the  grapes  grown  on  the 
11 '.ore  recent  alluvial  soils  and  bring  a  better  price  at  the  wineries. 
A  start  has  been  made  toward  putting  the  eroded  phases  of  the 
Pinole  loam  and  gravelly  loam  into  grapes,  and  the  prospects  are 
very  encouraging  so  far  as  the  growth  of  the  vines  is  concerned. 
There  is  some  apprehension  with  respect  to  markets.  For  a  number 
of  years  prices  have  been  satisfactory  and  profits  correspondinglj'^ 
high,  but  growers  fear  that  adverse  legislation  may  cripple  or  destroy 
the  market  for  wine.  Table  grapes  are  grown  in  a  small  way,  and 
it  is  claimed  that  many  varieties  do  very  well.  These  grapes  are  sold 
at  local  markets,  but  it  is  evident  that  these  markets  could  be  very 
easily  oversupplied.  No  raisin  grapes  are  grown,  as  the  climate  is 
not  suitable  for  curing  the  product. 

Casaba  melons  are  grown  for  seed  in  the  Potter  Valley  on  the 
heavier  members  of  the  Yolo  series  of  soils.  The  melons  do  very 
well  on  these  soils,  and  the  industry  has  assumed  considerable  local 
importance. 

In  the  northern  part  of  the  area,  especially  in  Redwood  Valley, 
considerable  land  remains  to  be  cleared.  The  clearing  as  a  rule  is 
done  at  odd  times  by  the  owners  and  it  is  difficult  to  give  the  cost 
per  acre.  There  are  few  very  large  stumps  to  be  taken  out,  the  oak 
stumps  being  the  most  difficult  to  remove.  The  cost  probably  is 
between  $25  and  $50  an  acre,  depending  on  the  nature  of  the  forest 
growth.  The  usual  custom  is  to  continue  the  clearing  over  a  number 
of  years,  which  allows  many  of  the  stumps  to  rot  out. 

No  data  concerning  the  size  of  farms  or  the  density  of  rural  popu- 
lation are  available.  The  impression  gained  from  observations  in 
the  field,  however,  is  that  the  population  in  the  valleys  proper  is  not 
so  dense  as  in  other  more  highly  developed  valleys  to  the  south.  The 
population  in  the  hill  country  on  the  borders  of  the  area  is  very 
sparse.  The  farms  have  never  been  large  compared  with  the 
bonanza  farms  of  the  San  Joaquin  and  Sacramento  Valleys,  and 
extensive  types  of  agriculture  have  never  developed.  The  farms  are 
of  medium  size.    In  a  few  cases  they  are  being  subdivided. 

The  annual  rainfall  of  this  area,  averaging  between  35  and  40 
inches,  is  considered  sufficient  for  all  agricultural  purposes.     This 


SOIL    SURVEY    OF    THE    UKIAH    AREA,    CALIFORNIA.  19 

rainfall  occurs  in  the  winter,  but  by  careful  cultivation  moisture  can 
be  conserved  and  made  to  last  throuMiout  the  summer.  The  farmers 
have  not  been  forced  to  ii-rigate,  as  the  rainfall  is  sufficient  to  give 
at  least  fair  returns  Avith  ordinary  farm  crops.  But  as  the  types  of 
farming  have  become  more  intensive  of  late  years  the  need  of  irri- 
gation has  been  felt.  No  general  irrigation  system  has  been  at- 
tempted, but  a  number  of  farmers  have  established  individual  sys- 
tems. There  has  been  a  small  amount  of  gravity  irrigation  from 
springs  on  some  of  the  hill  farms,  but  the  water  so  far  utilized  has 
been  obtained  mainly  by  pumping  from  the  Russian  River  or  from 
the  underlying  gravels.  The  Russian  River  in  the  summer  often  has 
no  surface  flow,  but  there  is  always  a  strong  flow  through  the  gravels 
below  the  bed.  This  has  been  utilized  by  a  few  farmers  along  the 
banks  of  the  river.  The  water  is  pumped  by  electric  or  gasoline 
power  to  a  height  of  15  to  25  feet,  and  is  distributed  over  the  field 
by  gravity.  Such  irrigation  so  far  has  been  used  only  for  alfalfa 
and  garden  crops.  Many  of  the  side  streams  that  enter  the  valley 
are  fed  by  springs  and  have  a  perennial  flow  through  their  courses 
in  the  hills.  But  as  soon  as  t\\ej  reach  the  valley  floor  the  waters 
sink  into  the  gravel  and  there  is  no  surface  flow  except  during  the 
rainy  season.  Unquestionably  permanent  sources  of  water  supply 
could  be  obtained  near  these  streams  if  the  gravel  beds  could  be 
reached,  but  the  extent  of  the  gravel  is  not  certain.  Some  wells  on 
the  uplands,  away  from  the  streams,  might  prove  permanent.  Others 
would  certainly  be  only  temporary.  The  chances  of  getting  a  cer- 
tain water  supply  seem  better  as  the  center  of  the  valley  or  the  beds 
of  the  side  streams  are  approached. 

The  drainage  of  McDowell  Valley  passes  out  through  a  gorge  cut 
in  bedrock.  This  stream  goes  dry  in  the  summer,  and  unless  there  is 
some  subterranean  outlet  to  the  drainage  of  the  valley,  Avhich  seems 
improbable,  this  indicates  that  there  is  no  excess  supply  of  water  in 
the  gravels  underlying  McDowell  Valley  and  no  large  water  supply 
for  irrigation  purposes. 

Potter  Valley  seems  to  have  a  large  supply  of  subterranean  water, 
which  might  be  pumped  for  irrigation.  There  is  always  a  stream  of 
water  flowing  out  of  the  valley  through  the  rock-bottomed  gorge 
of  the  East  Fork.  The  amount  of  outflow  has  increased  since  the 
headwaters  of  the  Eel  River  have  been  diverted  and  brought  to 
Potter  Valley  for  power  development.  It  has  been  proposed  to  use 
the  water  from  this  power  plant  for  irrigation,  as  it  could  be  taken 
by  gravity  to  all  parts  of  the  valley,  but  so  far  only  a  very  little  is 
used.  The  farmers  state  that  the  supply  is  intermittent  and  that 
water  is  likely  to  be  lacking  when  most  needed.  The  company  man- 
aging this  plant  has  undeveloped  reservoir  sites  which,  when  devel- 


20  FIELD   OPZRATIOXS   OF    THE   BUREAU    OF   SOILS,  1914. 

oped,  will,  it  is  cliiin«?d,  enable  them  to  run  constantly,  and  in  this 
case  the  water  from  their  plant  will  be  a  valuable  asset  to  t^ie  valley 
for  irrigation. 

The  value  of  land  in  the  area  has  increased  greatly  w^ithin  the  last 
few  years.  The  best  alluvial  lands  are  selling  at  prices  ranging  from 
$200  an  acre  for  unimproved  land  to  $r)00  an  acre  for  land  in  bearing 
vineyards,  orchards  or  hop  yards.  The  bench  lands  sell  for  $75  to 
$200  an  acre,  according  to  improvements.  The  hill  lands  suitable 
only  for  pasture  are  valued  at  $5  to  $20  an  acre.  Some  of  the  hill 
land,  covered  only  with  chaparral,  is  practically  worthless. 

Very  little  hardpan  is  encountered  in  the  area,  and  it  has  no  in- 
fluence on  the  land  values.  Some  hardpan  outcrops  on  the  hillsides 
of  the  very  oldest  valley  filling.  Where  observed  this  is  about  a  foot 
thick,  of  medium  hardness,  brown  in  color,  and  contains  waterworn 
cobbles, 

A  large  part  of  the  labor  on  the  small  ranches  is  performed  by 
the  owners.  The  Indians  in  the  area  are  employed  as  laborers  in 
the  hop  fields.  They  are  also  employed  to  clear  land  and  cut  wood  in 
the  winter  and  in  a  small  way  to  do  general  farm  work.  Numbers 
of  Japanese  are  employed  in  the  hop  fields  and  in  the  vineyards  and 
orchards.  There  is  a  fair  supply  of  white  labor  at  all  times,  and 
during  the  busy  season  of  hop,  fruit,  and  grape  picking  this  is  aug- 
mented by  an  abundance  of  transient  labor.  Wages  are  comparable 
with  those  paid  in  adjoining  parts  of  the  State. 

SOILS. 

The  valleys  in  the  Ukiah  area  have  had  a  complicated  geomorphic 
history  that  has  not  yet  been  entirely  worked  out.  Holway  has 
studied  some  of  the  problems,  and  the  following  discussion  is  based 
on  his  work,^  supplemented  by  observations  of  the  field  party. 

It  seems  certain  that  all  the  territory  lying  west  of  the  eastern 
boundary  of  Mendocino  County  and  embracing  the  area  surveyed  was 
at  one  time  reduced  to  a  peneplain  surface  and  drained  directly  west- 
ward into  the  Pacific  Ocean.  In  the  latter  part  of  the  peneplain 
period,  probably  near  the  beginning  of  Quaternary  time,  there  were 
local  foldings  and  an  uplift  of  the  region  as  a  whole.  The  main 
foldings  have  been  accompanied  and  followed  at  different  times  by 
minor  foldings  or  faults.  A  great  many  of  these  have  occurred.  A 
long,  straight  valley  was  formed  parallel  to  the  general  direction  of 
the  Coast  Eange  in  this  locality.  Apparently  the  northern  part  of 
this  valley  was  the  result  of  a  syncline  and  the  low^er  part,  in  what 
is  now  the  gorge  of  the  Russian  River  in  the  southern  part  of  the 


1  Holway,  "  The  Russian  River,  a  Characteristic  Stream  of  the  California  Coast  Ranges,' 
Univ.  Cal.  Pub.  in  Geog.,  vol.  1,  No.  1. 


SOIL   SURVEY   OF    THE   UKIAH   AEEA,   CALIFORNIA.  21 

area,  may  be  considered  a  '"fault-line  valley,"  that  is,  a  valley  pro- 
duced by  erosion  but  following  the  line  of  a  fault  because  along  such 
line  erosion  was  easiest.  The  Russian  River  in  its  headward  erosion 
from  the  south  has  been  guided  by  these  faults  and  foldings  and  has 
entered  and  drained  this  large  valley.  Therefore  the  depression,  in- 
cluding the  main  agricultural  valleys,  is  considered  a  structural 
valley,  and  the  gorge  in  the  southern  part  of  the  area  an  erosional 
valley. 

The  main  structural  valley  just  mentioned,  produced  by  the  syn- 
cline  which  includes  the  arable  valleys  of  Redwood,  Calpella,  Coyote, 
and  Ukiah,  was  a  large,  elliptical  depression  extending  from  the  head 
of  Redwood  Valley  to  the  southern  end  of  Ukiah  Valley,  a  distance 
of  about  18  miles,  and  averaging  through  most  of  its  length  from 
3|  to  4^  miles  wide.  This  originally  large  valley  has  been  modified 
by  later  developments  in  the  rising  and  sinking  of  small  parts  and  by 
being  filled  partly  or  entirely  by  deposits  of  alluvial  fans  or  deltas 
from  the  side  streams,  notably  Forsj^the  Creek,  and  the  east  fork  of 
Russian  River.  Immense  quantities  of  material  Avere  deposited  in 
the  valley.  The  actual  depth  of  this  old  valley  filling  is  not  known. 
One  well  in  the  southeastern  part  of  Potter  Valley  was  bored  400 
feet  through  blue  clays  which  are  probably  old  valley-filling  material. 
It  probably  is  1,000  feet  thick  in  places.  It  has  been  eroded  consider- 
ably since  the  first  deposition  and  either  carried  away  or  reworked, 
but  large  remnants  of  the  first  filling  still  remain.  These  remnants  are 
high  and  are  badly  eroded,  and  for  the  most  part  are  nonarable,  thus 
decreasing  the  size  of  the  arable  part  of  the  valley  and  dividing  it 
up  into  smaller  valleys.  From  an  agricultural  standpoint  this  oldest 
eroded  valley  filling  differs  little  from  the  adjoining  mountain  slopes. 
The  later  reworked  portions  of  this  old  valley  filling  takes  the  form 
of  river  terraces  and  is  arable.  South  of  this  main  valley,  which 
extends  to  the  vicinity  of  Henry  station,  are  smaller  ones,  partly 
structural  and  partly  erosional  in  origin  and  having  a  more  com- 
plicated geomorphic  history  than  the  large  valley  just  described. 
Potter  Valley  evidently  lies  in  another  syncline  which  has  had  several 
lesser  tiltings  and  which  has  been  drained  by  the  cutting  down  of 
the  gorge  across  the  ridge  to  the  southwest. 

The  large  main  valley  received  all  the  streams  to  the  east  and  also 
the  headwaters  of  the  streams  to  the  west  for  a  short  distance.  This 
explains  the  peculiar  direction  of  flow  of  such  streams  as  Morrison 
and  McDowell  Creeks.  They  evidently  have  not  been  developed  as 
tributaries  of  the  present  Russian  River,  else  they  would  have  a 
southwest  trend.  As  it  is,  they  have  a  northwest  trend  and  are  in 
line  with  streams  on  the  west  side  of  the  Mendocino  Ridge  that  flow 
into  the  ocean.  They  apparently  are  captured  headwaters  of  these 
streams. 


22  FIELD   OPERATIONS   OF    THE   BUREAU   OF    SOILS,  1914. 

It  seems  probable  that  early  in  their  historj'^  these  valleys  were 
lakes,  for  in  the  substratum  of  the  old  soils  there  are  beds  of  silts 
and  clays  that  must  have  been  laid  down  in  very  quiet  water. 

At  the  present  time  all  the  valleys  are  drained.  This  apparently 
has  resulted  from  the  combined  action  of  the  cutting  down  of  the 
gorge  at  the  south  end  of  the  vallej's  giving  an  outlet  to  the  waters, 
from  the  filling  of  the  valleys  above  referred  to,  and  probably  from 
some  crustal  movements. 

The  rocks  forming  the  hills  surrounding  the  Ukiah  area  apparently 
belong  largely  to  the  Franciscan  series,  which  are  described  as  prob- 
ably of  Jurassic  age  ^  and  consist  of  sandstones,  shales,  and  conglom- 
erates which  have  undergone  metamorphism.  Some  of  these  rocks 
have  been  little  changed  and  others  have  been  greatly  changed. 
Some  are  very  soft  and  weather  and  erode  rapidly,  while  others  are 
,  harder  and  weather  much  slower,  giving  a  more  rugged  outline  to 
the  hills  formed  by  them.  Among  the  harder  rocks  are  the  radio- 
larian  cherts.  Included  with  these  sedimentary  rocks  are  a  number 
of  igneous  intrusives,  some  of  which  also  have  suffered  great  meta- 
morphism. The  igneous  rocks  are,  first,  basalt  or  diabase,  and, 
?econd,  periodites  which  have  in  general  become  thoroughly  serpen- 
tinized.  The  beds  and  strata  of  these  various  rocks  have  been  very 
much  tilted,  broken,  and  warped.  In  practically  no  case  are  the 
sedimentary  rocks  horizontal,  as  they  undoubtedly  were  when  they 
were  laid  down,  but  they  are  found  now  at  all  angles  and  usually 
are  more  nearly  vertical  than  horizontal  in  position.  Furthermore, 
there  is  very  little  continuity  in  the  rocks.  The  fracturing  and  tilt- 
ing has  taken  place  in  great  detail.  As  a  result  of  this  the  residual 
soils  derived  from  these  rocks  have  very  frequent  changes  and  are 
extremely  difficult  to  map.  These  hills  evidently  have  occupied  their 
present  relative  position  for  a  long  time,  for  they  are  deeply 
weathered;  erosion  has  developed  a  drainage  system  that  has  reached 
ever}^  part  of  the  area,  and  the  hills  are  mainly  rounded  in  outline 
rather  than  rugged.  No  limestone  rock  was  observed  in  the  area, 
and  probably  little  is  present.  A  few  of  the  springs,  however,  carry 
a  high  percentage  of  lime  probably  extracted  from  the  minerals  of 
the  rocks  through  which  their  waters  circulate.  According  to  analy- 
ses (made  by  the  experiment  station  of  the  University  of  California) 
of  samples  collected  during  the  progress  of  this  survey,  the  soils  of 
the  area  carry  a  fair  percentage  of  lime,  from  0.50  per  cent  to  1.50 
per  cent,  but  this  apparently  is  largely  in  the  silicate  forms,  with 
only  small  amounts  in  the  carbonate  forms.  A  few  of  the  soils  show 
field  indications  of  being  mildly  acid,  others  apparently  are  neutral, 
and  the  soil  of  the  Dublin  series  gives  indications  of  having  a  high 
lime  content. 

1  San  Francisco  Folio,  U.  S.  Geol.  Survey,  1914,  by  A.  C.  Lawson. 


SOIL   SURVEY   OF   THE   UKIAH   AEEA,   CALIFOITNIA.  23 

The  soils  of  the  Ukiah  area  fall  into  three  general  groups:  (1) 
residual  soils;  (2)  soils  derived  from  old  valley-filling  material; 
and  (3)  soils  derived  from  recent  alluvial  deposits.  The  residual  soils 
result  from  the  disintegration  or  weathering  of  the  rocks  in  place. 
In  the  aggregate  these  form  a  very  small  proportion  of  the  valleys 
proper,  but  they  occur  extensively  in  the  hills  surrounding  the  val- 
leys. Only  small  areas  of  the  residual  soils  are  arable.  These  arable 
portions  occupy  low  hills  and  foot  slopes  at  the  edges  of  valleys,  very 
small  valleys  back  in  the  hills,  and  gentle  slopes  well  up  toward  the 
top  of  the  hills.  Perhaps  2  per  cent  of  the  hill  country  is  arable. 
The  arable  residual  soils  are  classed  with  the  Aiken  series,  including 
red  soils ;  the  Mariposa  series,  with  grayish-yellow  soils ;  the  Olympic 
series,  with  brown  soils;  and  the  Climax  series,  comprising  black 
soils.  The  rougher,  nonarable  portions  of  the  residual  soils,  in  Avhich 
differentiation  of  soil  series  and  types  is  not  warranted,  are  mapped 
as  Rough  mountainous  land,  which  includes  the  greater  part  of  the 
hills  and  mountains. 

The  second  group  of  soils  results  from  the  weathering  of  old  valley- 
filling  material.  This  material  has  been  brought  into  the  valley  dur- 
ing former  periods  by  streams  and  deposited  as  alluvial  fans,  deltas, 
and  lake  deposits.  The  deposits  have  been  reworked  in  part  a  num- 
ber of  times  by  streams  and  have  been  subjected  to  weathering  in 
place,  usually  with  the  development  of  rather  heavy  and  compact 
subsoils.  These  deposits  are  not  now  being  added  to  by  the  agencies 
that  originally  made  them,  but,  on  the  other  hand,  are  being  degraded 
by  erosion.  The  material  forming  these  soils  is  derived  from  all 
classes  of  rocks  found  in  the  hills.  The  soils  derived  from  the  old 
valley  deposits  are  classed  with  the  Corning  series,  comprising  the 
red  soils,  the  Pleasanton  series,  which  has  dark  grayish  brown  soils, 
and  the  Pinole  series,  with  light  brownish  yellow  or  grayish-yellow 
soils. 

The  third  general  division  includes  the  soils  formed  from  recent 
alluvial  deposits.  They  differ  from  the  old  valley-filling  deposits  in 
that  they  are  yet  in  process  of  formation,  have  not  been  "  aged  "  or 
weathered  in  place,  and  normally  have  rather  porous,  friable  subsoils. 
They  are  derived  from  all  classes  of  rock  material  eroded  from  the 
foothills  and  from  the  older  valley-filling  deposits.  The  soils  in  this 
division  are  classed  with  the  Honcut  series,  including  red  to  reddish- 
brown  soils;  the  Yolo  series,  Avith  brown  soils;  the  Tehama  series, 
with  brownish-yellow  or  grayish-yellow  soils;  and  the  Dublin  series, 
which  has  black  soils.  The  Yolo  series  have  stream-bottom  phases, 
which  are  river  flood  plain  soils.  They  differ  from  the  alluvial-fan 
soils  in  being  the  flood  plains  of  perennial  streams,  while  the  fans 
are  the  deposits  of  intermittent  streams.    This  third  di^  ision  includes 


24 


FIELD   OPERATIONS   OF    THE   BUREAU   OF   SOILS,   1914. 


Riverwash,    a    type    of   miscellaneous   material    of   nonagricultural 
character. 

The  following  table  gives  the  name  and  actual  and  relative  extent 
of  each  soil  tj'pe  mapped  in  the  area : 

Areas  of  different  soils. 


Poi!s. 

Acres. 

Per  cent. 

Soils. 

Acres. 

Per  cenl^ 

Rough  mountainous  land 

131,648 
10,816 
11,200 
2,816 
5,056 
4,352 
1,664 
5,760 
2,816 
128 

2,752 
2,368 
128 
2,176 
1,920 

67.7 
}          11.4 

4.0 

1           3.. 
3.0 

1      - 

1.4 
1            ..3 

1.1 

1.0 

1,920 
1,344 
960 
320 
896 
896 
768 
128 
256 
128 
320 
192 

192 

1.0 

Tehama  loam 

.7 

Pinole  loam 

.7 

Erodfed  jihase 

St  ream -bottom  phase 

.5 

Corning  loam 

.5 

Stream-bottom  phase 

.5 

Heavy  phase 

Yolo  silty  day  loam 

.2 
.2 

Stream-bottom  phase 

Yolo  fine  sandy  loam,  stream- 

Stream-bottom  phase 

Honcut  loam,  red  phase 

Tehama    silt    loam,    poorly 
drained  phase 

.1 

Corning  gravelly  loam 

.1 

Total  

Pieasanton  gravelly  loam 

193, 920 

Olympic  loam 

RESIDUAL  SOILS. 
Mariposa  Series. 

The  Mariposa  soil  is  pale  yellovv^  or  yellow  to  grayish  yellow^  or 
yellowish  brown  in  color.  The  subsoil,  where  present,  is- heavier 
than  the  surface  soil  and  as  recognized  in  this  survey  is  grayish 
yellow  or  pale  yellow  to  bluish  gray  in  color.  The  bluish-gray 
color  prevails  wherever  the  subsoil  extends  much  below  the  6-foot 
section.  The  subsoil  is  underlain  by  bedrock,  and  this  usually  oc- 
curs within  6  feet  of  the  surface. 

The  topography  is  rolling  or  hilly  to  mountainous,  and  drainage 
is  excessive,  but  the  hills  are  round  and  smooth,  broken  only  by 
occasional  steep-sided  ravines  or  marred  in  places  by  the  marks  of 
small  landslides.    Rock  outcrops  occur  in  places. 

The  Mariposa  series  is  residual  in  origin.  The  principal  basis  of 
differentiation  from  other  residual  soils  in  the  area  is  its  color.  It 
is  formed  mainly  by  the  weathering  of  the  softer,  unmetamorphosed 
or  slightly  altered  sandstones  and  shales  wiiich  are  probably  cor- 
related with  the  geological  formation  known  as  the  Franciscan  series 
of  rocks  and  which  are  intimately  interbedded,  upturned,  broken, 
and  generally  mixed.  Only  one  member  of  this  series,  the  Mariposa 
loam,  occurs  in  the  area.  As  mapped  it  may  include  minor  undif- 
ferentiated bodies  of  soils  of  the  Altamont  series,  which  includes 
brown  soils  of  similar  origin  but  is  not  recognized  in  this  area,  or 
of  soils  derived  from  old  valley-filling  deposits. 


SOIL    SURVEY    OF    THE    UKIAH    AREA,    CALIFORNIA.  25 


MARIPOSA    LOAM. 


The  soil  of  the  Mariposa  loam  consists  typical!}^  of  a  pale-yellow 
or  grayish-yellow  loam  from  1  to  '6  feet  deep,  though  in  this  survey 
the  type  includes  yellowish-brown  variations.  The  material  is  com- 
pact in  structure,  low  in  organic-matter  content,  and  difficult  to 
cultivate.  The  subsoil,  where  present,  is  a  claj^  loam  or  clay.  It  is 
compact  and  impervious  and  is  pale  yellow  or  brownish  yellow,  with 
bluish-gray  variations.  The  bluish-gray  material  is  found  at  lower 
depths,  next  to  the  parent  bedrock.  The  type  is  underlain  by  the 
shales  and  sandstones  from  which  it  is  derived,  and  these  may  occur 
directly  under  the  surface  soil  at  a  depth  of  1  or  2  feet,  or  lie  10  to 
20  feet  below  under  the  heavier  subsoil.  There  are  therefore  two 
variations  of  this  type,  one  with  a  shallow  soil  and  the  other  with 
a  deep  subsoil.  In  the  shallow  areas  there  is  little  or  no  subsoil, 
and  the  surface  soil  rests  directly  on  the  bedrock  at  a  depth  of  2  or 
3  feet,  with  an  occasional  outcropping  of  the  bedrock.  In  the  deeper 
areas  the  heavy  subsoil  is  always  present,  and  bedrock  may  not  occur 
within  the  6-foot  section.  These  variations  grade  into  each  other, 
and  they  are  not  separated  on  the  map  on  account  of  the  practical 
difficultv  of  examining  the  soil  section. 

The  Mariposa  loam  is  distributed  throughout  the  area,  occui-ring 
on  the  border  of  the  valleys  and  occupying  the  lower  foothills  or 
ridges.  It  is  bounded  on  the  side  away  from  the  valleys  by  Rough 
mountainous  land,  which  rises  to  higher  elevations.  In  many  places 
the  boundary  between  this  type  and  the  Rough  mountainous  land  is 
rather  arbitraiy.  The  topography  is  rolling,  but  the  hills  are 
rounded  and  smooth.  They  rise  from  100  to  200  and  even  400  feet 
above  the  general  level  of  the  adjoining  valley  floor.  These  hills  are 
parklike  in  appearance,  being  covered  with  native  grasses,  with  a 
sparse  growth  of  blue  oak,  valley  oak,  and  buckeye.  Manzanita 
grows  on  the  broken  slopes,  and  Douglas  fir  is  found  in  places.  In 
Potter  Valley  yellow  pine  and  digger  pine  are  found  on  the  soils 
of  this  series,  as  well  as  on  adjoining  soils  to  a  small  extent.  In  many 
places  the  surface  is  marked  b}'^  peculiar  irregularities  caused  by 
landslides.  These  may  cover  an  area  from  a  few  square  rods  to  an 
acre  in  size.  They  occur  where  the  soil  is  deeper  and  apparently 
are  caused  by  a  lessening  of  the  cohesion  through  the  saturation  of 
the  soil,  which  allows  the  soil  to  slide  on  the  compact  underlying 
clay.  Erosion  is  active,  but  the  surface,  except  for  occasional  ravines, 
is  not  broken  or  rough.    Drainage  is  good  to  excessive. 

The  type  is  used  for  pasture,  and  on  account  of  the  thin  forest 
growth  and  the  good  growth  of  grasses  it  is  highly  prized  for  this 
purpose.  Very  little  of  it  has  been  cultivated,  and  it  seemingly  has 
42235°— 16 4 


26 


FIELD   OPERATIONS  OF   THE  BUREAU   OF   SOILS,  1914. 


little  value  for  crop  production.    Grain  is  very  poor,  and  vineyards 
make  a  slow  growth  and  are  unproductive. 

Below  are  given  the  results  of  mechanical  analyses  of  samples  of 
the  soil  and  subsoil  of  the  Mariposa  loam : 

Mechanical  analyses  of  Mariposa  loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  f^n? 
sand. 

£ilt. 

Clay. 

573022     

Soil  

Per  cent. 
1.0 
1.1 

Percent. 
3.0 
3.0 

Per  cent. 
2.4 
1.9 

Per  cent. 
15.6 
11.9 

Percent. 
23.6 
17.3 

Per  cent. 
34.7 
34.4 

Percent. 
19.6 

573023 

Subsoil 

30.6 

Aiken  Sebies. 

The  soils  of  the  Aiken  series  are  red.^  The  subsoil  where  present 
has  the  same  color,  or  is  somewhat  lighter.  The  rock  from  which 
the  soil  is  derived  is  usually  between  2  and  4  feet  below  the  surface, 
but  in  a  few  places  it  may  lie  below  the  6-foot  section.  Rock  outcrops 
are  numerous.  The  topography  is  sloping  to  hilly,  and  surface 
drainage  usually  is  excessive.  The  slopes  in  many  places  are  quite 
steep. 

The  soils  of  the  Aiken  series  are  residual  in  origin  and  are  typically 
derived  from  igneous  and  metamorphosed  igneous  rocks  of  basic  or 
quartz-free  character.  As  occurring  in  this  survey  they  are  derived, 
apparently,  from  the  Franciscan  series  of  rocks,  for  the  most  part 
hard  and  highly  metamorpho.sed,  partly  sedimentary  and  partly 
igneous  in  origin. 

These  soils  are  differentiated  from  the  Mariposa  and  Climax  series 
on  the  basis  of  color,  but  it  is  found  also  that  the  Aiken  soils  are 
derived  prevailingly  from  the  metamorphosed  and  igneous  rocks 
rather  than  from  the  sedimentary  or  feebly  metamorphosed  sedi- 
mentary rocks  giving  rise  to  the  Mariposa  and  Climax  soils. 

As  mapped,  however,  the  soils  of  the  Aiken  series  probably  include 
locally  some  small  undifferentiated  areas  of  soils  which  are  derived 
from  the  sedimentary  rocks  and  which  if  more  extensive  would  be 
recognized  under  distinct  series  heads.  The  native  vegetation  of 
the  series  in  this  area  consists  of  oak,  fir,  redwood,  madrona,  man- 
zanita,  chamisal,  poison  oak,  and  a  varied  chaparral.  The  dense 
covering  of  trees  and  bushes  is  in  sharp  contrast  to  the  growth  on  the 
Mariposa  soil,  which  is  open  and  parklike. 

AIKEN   STONY  LOAM. 

The  Aiken  stony  loam  is  indicated  on  the  soil  map  by  stone  symbols 
in  color  of  the  Aiken  loam.     The  soil  is  a  red  or  brownish-red  to 

1  Yellowish-red  or  orange  Tariations  occur  in  the  present  area. 


SOIL   SURVEY    OF    THE   UKLA.H   AREA,   CALIFORNIA.  27 

rusty-red  loam,  containing  a  high  percentage  of  angular  fragments 
of  rock.  As  a  rule  these  fragments  gradually  increase  in  quantity 
with  depth,  bedrock  being  encountered  at  2  to  4  or,  in  extreme  cases, 
6  feet  below  the  surface.  The  soil  is  friable,  but  is  rather  difficult  to 
cultivate,  owing  to  its  stony  nature  and  the  prevailing  steeply  sloping 
surface. 

Only  two  small  areas  of  this  tjrpe  are  shown  on  the  map.  Both 
occur  in  the  southern  part  of  the  area,  one  near  Cummiskey  and  the 
other  on  the  Mendocino-Sonoma  County  line.  Other  bodies  too  small 
to  map  occur  within  the  Rough  mountainous  land  areas.  The  to- 
pography is  steep  to  hilly,  erosion  is  quite  active,  and  drainage  is 
excessive.  The  cleared  areas  of  this  soil  are  devoted  to  vineyards 
and  young  orchards,  to  which  the  soil  is  well  suited. 

AIKEN  LOAM. 

The  soil  of  the  Aiken  loam  is  typically  a  light-red  to  brownish-red 
or  yellowish-red  loam  usually  from  1  to  2  feet  deep,  but  in  places  having 
a  depth  of  4  feet.  The  yellowish  or  orange  tint  is  often  pronounced, 
and  is  much  more  strongly  developed  than  in  this  type  as  mapped 
elsewhere.  The  soil  is  of  friable  structure  and  is  easy  to  cultivate. 
It  contains  varying  quantities  of  angular  rock  fragments,  but  not 
enough  seriously  to  interfere  with  cultivation.  The  subsoil  where 
present  extends  from  the  surface  soil  to  the  bedrock,  and  usually  is 
light  red  or  even  yellow  in  color.  The  bedrock  is  encountered  in 
most-  places  at  depths  of  less  than  4  feet,  and  rock  masses  in  some 
places  outcrop. 

This  is  an  unimportant  type.  It  occurs  in  small  areas  at  the  base 
of  the  hills,  bordering  the  floors  of  the  valleys,  and  also  in  compara- 
tively level  areas  back  in  the  hills,  where  besides  the  areas  shown 
there  are  many  small  areas  too  small  to  map.  This  type  often  in- 
cludes some  undifferentiated  alluvial  or  colluvial  foot-slope  material 
on  the  lower  edge,  and  on  the  upper  margin  merges  with  the  liougli 
mountainous  land  lying  above  it.  It  is  sloping  to  steep  in  topog- 
raphy, and  occupies  some  of  the  more  nearly  level  parts  of  the  hi1' 
region.  It  is  all  arable,  but  some  of  it  is  so  steep  that  it  can  be  tilled 
only  with  difficulty.    Erosion  is  active  and  drainage  good. 

Cleared  areas  of  this  soil  are  used  for  the  production  of  fruit  and 
garden  crops.  It  is  productive,  but  its  value  is  limited  by  the  fact 
that  it  occurs  in  small  areas,  is  often  inaccessible,  and  lies  on  steep 
slopes.  As  the  development  of  the  region  progresses,  however,  more 
of  the  small  areas  of  this  soil  occurring  in  the  hills  probably  Av'ill  be 
brought  under  cultivation. 

Aiken  loam,  heavy  pJiase. — The  soil  of  the  Aiken  loam,  heavy 
phase,  varies  considerably  in  texture  and  color.  Prevailingly  it  is  a 
red  or  dark-red  heavy  loam   or  clay  loam  containing  some  small 


28 


FIELD   OPERATIONS   OF   THE   BUREAU   OF   SOILS,   1914. 


angular  fragments  of  the  parent  rock  but  not  enough  seriously  to 
aifect  cultivation.  In  this  survey  much  of  it  is  somewhat  deeper  red 
than  in  previous  survey's.  The  subsoil  is  similar  to  the  surface  soil 
in  color  and  texture,  but  contains  more  rock  fragments.  Bedrock  is 
found  at  varj'ing  depths,  but  lies  usually  between  3  and  5  feet  below 
the  surface. 

Only  one  area  of  this  phase  is  mapped,  a  narrow  strip  on  the 
eastern  edge  of  the  main  valley  near  Largo,  but  many  other  bodies 
too  small  to  map  separately  lie  within  the  areas  of  Rough  mountain- 
ous land. 

The  surface  is  sloping  to  rather  steep,  erosion  is  active;  and  drain- 
age is  fairly  good.  Some  undifferentiated  bodies  of  other  types, 
notably  the  Climax  clay  adobe,  too  small  to  be  shown  on  the  map, 
are  included  with  this  heavy  phase  of  the  Aiken  loam. 

The  phase  is  used  mainly  in  growing  grain,  of  which  the  yields  are 
good.    Some  orchards  have  been  set  out  on  it  recently. 

Results  of  mechanical  analyses  of  samples  of  soil  of  the  typical 
Aiken  loam  and  the  heavy  phase  follow : 


MccJianicdl  aiuiliises  of  Ail-ru  lotiiii. 


Nunil:or. 

Oewrii  ticn. 

Fine 
p  ravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

?ilt. 

(May. 

Typical:  573011 .  . 

Heavy  phase: 

573051 

Soil 

Per  cent. 
6.4 

9.S 

Per  cent. 
7.6 

10.6 

Per  cent. 
2.4 

4.2 

Per  cent. 
9.9 

Per  cent. 

18.  S 

Per  cent. 

?.9. 3 

Per  cent. 
15.9 

:                   i 
9.  G               S.  4             32.4 

25.1 

Ol.Y.MI'lC    SkUIES. 


The  soils  of  the  Olympic  series  are  brown  to  rather  dark  brown; 
the  subsoil,  where  present,  is  gray  or  grayish  brown  to  brown  in 
color, and  of  similar  or  somewhat  heavier  texture  and  more  compact 
structure  than  the  surface  material.  Bedrock  usually  is  encountered 
Avithin  6  feet  of  the  surface,  and  there  are  frequent  areas  of  shallow 
soil  marked  by  rock  outcrop.  The  topography  is  rolling  to  steep  and 
hilly,  and  drainage  thorough  to  excessive. 

The  Olympic  soils  are  residual  in  origin  and  are  derived  from  basic 
igneous  and  ni(<tamorphic  rocks.  In  this  area  thev  are  derived  almost 
entirely  from  metamorphosed  igneous  rocks,  among  which  serpentine 
is  very  conspiciiou.s.  They  are  differentiated  from  the  Climax  soils, 
with  which  they  are  closely  associated  in  origin  and  occun-ence,  on 
the  basis  of  color,  the  Olympic  soils  being  brown  and  the  Climax 
soils  black.  They  are  distinguished  from  the  ]Mariposii  soils  also  by 
color,  but  tlic  I'ocks  which  produce  tlicin  h;ivc  a  larger  proportion  of 


SOIL   SUKVEY    OF    THE   UKIAH   AREA,   CALIFORNIA,  29 

the  basic  igneous  and  highly  metamorphosed  igneous  rocks  than  the 
Mariposa  soils. 

In  this  area  the  surface  of  the  Olympic  soils  in  places  is  smooth, 
but  in  other  places  it  is  marked  by  old  slips  or  landslides.  The  native 
vegetation  is  mainly  grass.  There  is  a  scattering  of  trees,  with  a 
thicker  growth  in  the  ravines  and  on  very  steep  slopes. 

As  mapped  these  soils  ma}^  include  small  undifferentiated  areas  of 
black  soils,  which  in  this  survey  are  recognized  as  the  Climax  series, 
and  of  brown  residual  soils  derived  from  sedimentary  and  only  feebly 
metamorphosed  rocks. 

OLYMPIC    STONY   LOAM. 

The  Olympic  stony  loam  is  shown  on  the  soil  map  by  stone  sym- 
bols iji  the  Olympic  loam  color.  The  soil  and  subsoil  are  similar 
to  those  of  the  OWmpic  loam,  except  for  the  large  content  of  angu- 
lar rock  fragments  in  the  soil  and  subsoil  and  on  the  surface.  Out- 
crops of  bedrock  are  also  more  frequent  than  in  typical  areas  of  the 
Olympic  loam,  and  it  is  probable  that  the  average  depth  to  bedrock 
is  not  so  great. 

Several  areas  occur  on  the  east  and  north  sides  of  Potter  Valley 
and  most  of  the  cultivated  soil  at  Cummiskey  is  of  this  type.  The 
topography  is  sloping  to  steep,  erosion  is  active,  and  drainage  is  ex- 
cessive. The  areas  in  Potter  Valley  are  in  pasture,  and  the  cleared 
land  at  Cummiskey  is  devoted  to  grain  and  grapes.  This  soil  seems 
well  adapted  to  grapes,  but  the  topography  renders  cultivation  dif- 
ficult. It  lies  from  100  to  400  feet  above  the  river,  and  the  fields  are 
bordered  by  ravines  and  precipitous  slopes  too  steep  for  agricultural 
use. 

OLYMPIC    LOAM. 

The  soil  of  the  Olj'^mpic  loam  is  light  brown  or  grayish  brown  to 
dark  brown,  and  has  a  rather  compact  structure.  It  varies  in  depth 
from  1  to  3  feet,  and  contains  some  angular  rock  fragments.  The 
subsoil,  where  present,  is  very  similar  to  the  surface  soil  both  in 
color  and  in  texture.  The  rock  from  which  the  soil  is  obtained  is 
usually  encountered  at  depths  of  2  to  5  feet,  and  in  a  few  places 
outcrops. 

The  Olympic  loam  is  mapped  in  several  areas  on  the  east  side  of 
Potter  Valley,  in  two  areas  just  north  of  Largo,  and  in  two  small 
bcdies  in  the  southern  part  of  the  area  surveyed.  Its  topography  is 
gently  sloping  to  steep.  Erosion  is  active,  and  drainage  is  well 
established.  At  present,  the  Olympic  loam  is  used  almost  exclusively 
for  pasture,  for  which  it  seems  well  suited.  So  little  of  it  has  been 
cultivated  that  it  is  impossible  to  say  definitely  what  its  agricultural 
possibilities  are.  but  the  prospects  are  not  very  encouraging. 


30  FIELD    OPERATIONS   OF    THE    BUREAU    OF    SOILS,   1914. 

Cmmax  Skkiks. 

The  soils  of  the  Climax  series  are  dark  gra^'  to  black,  and  rest 
on  subsoils  usually  of  brown  or  yellow  color.  Bedrock  underlies 
all  the  areas  covered  by  these  soil  types  at  shallow  depths,  usually 
wit*in  the  6-foot  section.  There  are  many  areas  of  thin  or  shallow 
soils  and  rock  outcrop 

The  soils  of  this  series  occur  in  moderately  hilly  to  mountainous 
districts.  The  soils  are  residual,  being  derived  from  metamorphosed 
rocks,  probably  of  basic  igneous  origin,  among  which  serpentine  is 
very  often  present.  They  are  closely  allied  to  the  Olympic  soils  in 
origin  and  mode  of  formation,  but  differ  in  color,  the  Olympic 
soils  being  brown  and  the  Climax  soils  black.   . 

In  this  survey  the  Climax  clay  adobe  is  the  only  member  of  the 
series  mapped.  The  topography  is  moderately  hilly  or  sloping,  and 
the  surface  is  smooth.  The  vegetation  consists  entirely  of  her- 
baceous plants. 

CLIMAX     CLAY      ADOBE. 

The  Climax  clay  adobe,  owing  to  its  small  and  rather  indefinite 
extent,  is  indicated  on  the  soil  map  by  inclusion  symbols  in  areas 
of  the  Olympic  loam.  The  soil  is  a  dark-gray  to  black  clay  from 
18  to  24  inches  deep.  It  has  a  pronounced  adobe  structure,  becomes 
very  sticky  when  wet,  bakes  and  checks  upon  drying,  and  is  ex- 
tremely difficult  to  cultivate.  The  soil  grades  into  a  dark  grayish 
brown  or  yellowish-brown  clay,  which  in  turn  rests  upon  bedrock 
at  4  to  6  feet  below  the  surface.  This  soil  is  apparently  well  sup- 
plied with  organic  matter  and  lime.  Under  normal  conditions  it  is 
black  or  nearly  so,  but  the  surface  when  extremely  dry  and  bleached 
•by  the  sun,  especially  if  powdered,  has  a  light-gray  color.  The 
dark  color  returns,  however,  as  soon  as  the  soil  is  made  wet. 

Two  small  areas  of  the  Climax  clay  adobe  are  mapped  on  the 
east  side  of  Potter  Valley,  but  many  small  bodies  from  a  few  square 
rods  to  a  few  acres  in  size  and  too  small  to  be  shown  on  the  map  are 
scattered  over  the  low  hills  bordering  the  valley  throughout  most  of 
its  length,  and  are  included  with  areas  of  tlie  Olympic  and  other 
residual  soils  ai^d  Rough  mountainous  land. 

The  topography  is  nearly  level  to  sloping,  and  erosion  is  moder- 
ate. Most  of  the  type  is  in  pasture.  A  few  small  bodies  included  in 
other  types  are  under  cultivation,  and  are  fairly  productive  though- 
very  hard  to  cultivate. 


SOIL    SURVEY    OF    THE    UKIAH    AREA,    CALIFORNIA. 


31 


The  following  table  gives  the  results  of  mechanical  analyses  of 
sanjples  of  the  soil  and  subsoil  of  this  type: 

Mechanical  analyses  of  Climax  clay  adobe. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

673030 

Soil 

Per  cent. 
1.5 
1.3 

Per  cent. 
2.1 
2.6 

Per  cent. 
1.1 
1.2 

Per  cent. 
5.6 
5.6 

Per  cent. 
9.4 
9.4 

Per  cent. 
33.6 
34.0 

Per  eerU. 
46.8 

673031 

Subsoil 

45.8 

M  [SCELLANEOUS. 


ROUGH     MOUNTAINOUS     LAND. 


The  Eough  mountainous  land  includes  most  of  the  hill  land  bor- 
dering the  valley  proper  on  both  sides.  (PI.  II,  fig.  2.)  Very 
little  of  the  surface  can  be  classed  as  Eough  stony  land  or  Rock 
outcrop,  but  the  land  is  too  steep  to  plow  and  is  nonarable  mainly 
for  that  reason.  Most  of  the  hills  are  covered  with  residual  soils, 
mainly  of  the  Mariposa  and  Aiken  series,  with  some  of  the  Olympic 
and  Climax  series.  The  soil  is  shallow  and  subject  to  severe  erosion. 
Small,  detached  areas  of  arable  land  are  scattered  through  the  hills, 
on  the  gentler  slopes  or  in  small  valleys.  Some  of  these  have  been 
cleared  and  farmed.  Others  no  doubt  will  later  be  brought  under 
cultivation,  but  the  total  arable  area  is  very  small,  probably  not  more 
than  2  per  cent  of  the  area  mapped  as  Rough  mountainous  land. 
Some  of  the  gentler  hills,  those  derived  from  the  softer  sandstones 
and  shales,  are  grass  covered  with  a  scattered  growth  of  valley  oak 
<5r  blue  oak,  which  gives  them  a  parklike  appearance.  These  hills 
are  rounded  in  outline,  with  only  occasional  rock  outcrops.  The 
soils  are  yellow  or  gray  in  color.  The  hills  of  this  character  gradu- 
ally give  way  to  steeper  hills  of  harder  rocks — metamorphosed  sedi- 
mentary rocks  or  igneous  intrusions — with  shallower,  mainly  brown 
or  red  soils,  and  more  numerous  rock  outcrops.  The  vegetal  cover- 
ing includes  trees  and  shrubs.  Douglas  fir  and  redwood  grow  in  the 
ravines  and  on  sheltered  hillsides,  and  oaks  of  various  species  on 
many  of  the  medium  slopes.  Many  of  the  more  exposed  hilltops 
have  no  trees  but  are  covered  with  chaparral. 

The  Rough  mountainous,  land  is  valuable  for  pasture,  the  more 
open  hills  affording  much  the  best  pasturage  for  sheep  and  cattle. 
The  timber  is  valuable  for  firewood  and  charcoal.  All  timber  suit- 
able for  sawing  into  lumber  has  long  ago  been  removed. 

The  small  included  areas  of  arable  land  are  often  well  suited  to 
fruit  culture.'  Even  oranges  are  grown  on  the  hills  500  feet  above 
the  valley  floor,  though  it  is  entirely  impracticable  to  grow  them 


32  FIELD    OPERATIONS   OF    THE    BUREAU    OF    SOILS,    1914. 

t 

in  the  valley.    They  are  grown  only  in  isolated  cases,  however,  and 
not  commercially. 

SOILS   DEKI\7CI)   FKOM   OLD   VALLEY-FILLING    MATP^RIAL. 
Corning  Seiuks. 

The  soils  of  the  Corning  series  are  pale  red  or  yellowish  red.  The 
subsoils  are  pale  red  or  red,  occasionally  yellowish,  and  heavier  and 
more  compact  than  the  surface  soil. 

In  exposed  sections  stratified  beds  of  cobbles,  gravels,  sands,  and 
finer  materials  of  compact  or  partially  cemented  structure  occur  at 
4  to  8  feet  below  the  surface.  It  is  probable  that  this  substratum  is 
present  throughout  the  series  in  this  area,  but  this  could  not  be  de- 
termined in  all  cases. 

The  Corning  series  is  derived  from  old  valley-filling  material,  hav- 
ing its  source  in  a  variety  of  rocks.  In  origin  and  mode  of  formation 
it  is  similar  to  those  of  the  Pleasanton  and  Pinole  series,  and  it  is 
differentiated  from  them  on  the  basis  of  color.  In  this  survey  much 
of  the  parent  material  seems  to  have  been  deposited  as  old  alluvial 
fans  and  to  some  from  sandstones,  shales,  conglomerates,  and  in- 
trusives  of  the  Franciscan  series  of  rocks. 

The  soils  occupy  gently  sloping  to  rolling  terraces  or  benches. 
The  surface  is  usually  smooth,  although  in  some  high  dissected  areas 
the  slopes  may  be  steep.  The  native  vegetation  consists  of  white  oak, 
black  oak,  and  live  oak,  Douglas  fir,  madrona,  manzanita,  and  various 
pmall  trees  and  bushes,  for  the  most  part  forming  a  dense  growth. 
Where  the  clay  subsoil  approaches  the  surface,  hindering  drainage, 
the  forest  covering  is  scattered  and  parklike,  or  gives  way  entirely 
to  a  covering  of  grass.  In  Potter  Valley  the  covering  is  parklike,  and 
some  yellow  pine  is  found. 

CORNING   LOAM. 

The  soil  of  the  Corning  loam  is  predominantly  a  pale-red  or  yel- 
lowish-red loam,  containing  some  gravel,  and  from  12  to  24  inches 
deep.  The  subsoil  is  a  tenacious  clay  loam  or  clay,  pale  red  or  brown- 
ish red,  or  even  yellow  in  color,  and  usually  containing  considerable 
gravel.  It  is  underlain  at  depths  of  4  to  8  feet  by  a  substratum  of 
chiy  containing  cobbles  and  gravel,  partially  cemented  and  unfavor- 
able to  the  passage  of  water  and  penetration  of  roots.  In  bleached 
surfaces,  especially  where  finely  pulverized,  the  soil  has  a  yellow 
color. 

Two  areas  of  this  type  are  mapped  on  the  east  side  of  Redwood 
Valley,  several  areas  are  found  in  Potter  Valley,  and  two  small  areas 
occur  near  Guidiville.    The  topograph}^  is  level  to  gently  rolling  and 


Report  of  Bureau  of  Soils,  U.  S.  Dept.  of  Agriculture,  1914. 


Plate  III. 


it  i.iii^  iiiii  tJflTlTillllill  H  i  ■  i  1  y  ftVlit  i  ■<  I  M^  »  *  «»^  ■'!»,.. «  .  »■.»  ^i «« '. 


Fig.  1.— Hops  on  Stream-Bottom  Soils  of  the  Yolo  Series. 


Fig.  2.— Dry-Wine   Grapes  on    Pinole   Gravelly    Loam,   Old   Valley-Filling 

Material. 

Slopes  in  background  consist  of  the  eroded  phase  of  this  type. 


Report  of  Bureau  of  Soils,  U.  S.  Dept.  of  Agriculture,  1914. 


Plate  IV. 


Fig.  1  .—Section  in   Material  of  Corning  Gravelly   Clay  Loam,  Old  Valley- 
Filling  Material. 


Fig.  2.— Peach  Orchard  on  Corning  Gravelly  Clay  Loam,  North  of  Coyote 

Valley. 


Report  of  Bureau  of  Soils,  U.  S.  Dept.  of  Agriculture,  1914. 


Plate  V. 


Fig.  1.— Section  in  Old  Valley-Filling  Material  of   Pinole  Gravelly  Loam, 

NEAR    UKIAH. 


Fig.  2.— Stream-Bottom  Soils  of  the  Yolo  Series,  near  Ukiah. 

Terraces  in  distance  occupied  by  soils  of  old  valley-lilliiig  material. 


SOIL    SURVEY    OF    THE    UKIAH    AREA,    CALIFORNIA. 


33 


the  surface  smooth.    Drainage  is  good,  except  in  a  few  places  where, 
owing  to  an  impervious  subsoil,  it  is  deficient. 

The  Corning  loam  in  the  Potter  Valley  is  mainly  in  pasture.  That 
in  Redwood  Valle}^  is  partly  uncleared;  the  cleared  portion  has  been 
used  for  pasture  and  grain  production,  but  some  of  it  is  now  set  to 
fruit. 

Results  of  mechanical  anah'ses  of  samples  of  soil  and  subsoil 
follow : 

Mechanical  analyses  of  Corning  loam. 


Numl:)er. 

Description. 

Fine, 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 

sand. 

Very  finp 
sand. 

Silt. 

Clay. 

573032 

Soil 

Per  cent. 
4.6 

5.4 

Per  cent. 
7.1 
12.0 

Per  cent. 
4.6 
6.2 

Per  cent. 
16.2 
18.9 

Per  cent. 
19.2 
12.4 

Per  cent. 
32.8 

25.8 

Per  cent. 
15.5 

573033  

Subsoil 

19.6 

CORNING  GU.WELI.Y  LOAM. 


The  surface  soil  of  the  Corning  gravelly  loam  is  a  pale-red  to 
brownish-red  loam  from  18  to  36  inches  deep,  containing  large 
quantities  of  waterworn  gravel,  consisting  mainly  of  quartzite  ma- 
terial. The  subsoil  is  a  pale-red  or  brownish-red  to  yellowish  clay 
loam  or  clay,  containing  varying  quantities  of  gravel,  in  some  places 
sufficient  to  give  a  gravelly  clay.  It  is  underlain  at  varying  depths, 
usually  below  6  feet,  by  the  typical  substratum  of  the  Corning  series. 
When  the  soil  is  dry  and  powdery  it  is  dull  yellow,  the  typical  red 
color  being  seen  in  freshly  plowed  fields. 

A  large  area  of  this  soil  occurs  on  the  east  side  of  Redwood  Valley, 
and  small  areas  in  Potter  Valley,  near  the  Yokayo  Rancheria,  north- 
west of  Ukiah,  northwest  of  Central  School,  and  south  of  Old  Hop- 
land.  It  occupies  low  terraces,  with  smooth  and  sloping  to  gently 
rolling  surfaces.  Erosions  are  seen  in  places,  but  well-defined  drain- 
age channels  do  not  as  yet  reach  all  parts  of  the  areas.  Some  of  this 
soil  lacks  surface  drainage,  and  the  subdrainage  is  generally  more 
or  less  retarded  by  the  compact  substratum. 

INfuch  of  the  Corning  gravelly  loam  is  uncleared  and  is  densely 
covered  with  oak,  Douglas  fir,  madroila,  and  brushy  undergrowth. 
Some  of  it,  farmed  to  grain,  has  proved  fairly  productive. 

On  a  part  of  it  orchards  are  being  planted. 

Corning  gravelly  loam,  eroded  j)hase. — The  Corning  gravelly  loam, 
eroded  phase,  which  is  indicated  on  the  soil  map  by  crosslines  over 
Corning  gravell}'^  loam  color,  covers  a  small  area  in  the  western  part 
of  Potter  Valley.  It  occupies  a  high  position,  and  is  so  badly  eroded 
that  its  agricultural  value  is  materially  impaired.  It  has  the  general 
characteristics  of  the  typical  Corning  gravelly  loam,  but  differs  in  its 


34 


FIELD   OPEEATIONS   OF    THE   BUREAU   OF    SOILS,  1914. 


topography.    The  slopes  are  generally  steep  and  drainage  is  excessive. 
The  area  occupied  by  this  phase  is  still  uncleared  and  undeveloped. 

The  following  table  gives  the  results  of  mechanical  analyses  of 
samples  of  the  typical  soil  and  subsoil  of  the  Corning  gravelly  loam: 

Mechanical  analyses  of  Corning  gravelly  loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

573009 

Soil 

Per  cent. 

7.8 
3.0 

Per  cent. 
6.3 
4.0 

Per  cent. 
2.6 
2.0 

Per  cent. 
10.3 
8.2 

Per  cent. 
15.0 
13.4 

Per  cent. 
41.0 
34.1 

Per  cent. 
16.9 

573010  

Subsoil 

35.3 

CORNING  GRAVELLY  CLAY  LOAM. 

Owing  to  its  small  extent,  the  Corning  gravelly  clay  loam  is  indi- 
cated on  the  soil  map  by  inclusic  n  symbols  in  the  color  of  the  Corning 
loam.  The  surface  soil  is  a  dark-red  clay  loam  about  2  feet  in  depth, 
containing  subangular  gravel.  The  subsoil  is  a  red  to  mottled  red  and 
yellow  clay  loam  to  clay,  containing  gravel,  passing  into  the  gravelly 
substratum  below  a  depth  of  6  feet.  The  red  color  of  both  the  soil 
and  subsoil  is  much  darker  than  that  of  the  other  soils  of  this 
series  in  the  area.  The  substratum  is  a  mass  of  angular  or  suban- 
gular cobblestones  from  1  to  4  inches  in  diameter.  (PI.  IV,  fig.  1.) 
The  greater  part  of  this  material  is  quite  thoroughly  w^eathered, 
and  is  easily  broken  with  the  geologist's  hammer.  The  surface  soil 
has  evidently  been  produced  by  the  advanced  disintegration  and 
w^eathering  of  this  material  and  contains  angular  fragments  about 
the  size  of  small  gravel,  which  have  resulted  from  the  breaking  down 
of  the  harder  cobbles.  The  finer  soil  material  has  come  from  the 
breaking  down  of  the  fragments  of  softer  rock. 

One  area  of  this  soil  occupies  a  remnant  of  a  high  terrace  or  old 
alluvial  fan  just  north  of  Coyote  Valley.  This  area  slopes  gently 
to  the  west  and  north  and  has  a  fairly  smooth  surface.  Erosion  is 
more  or  less  active  and  drainage  is  good.  Some  small  bodies  of 
soils  of  lighter  texture  belonging  to  the  same  series,  which  are  too 
small  to  be  shown  separately  on  the  soil  map,  are  included.  The 
color  of  soil  in  these  areas  is  lighter,  in  places  being  brownish  gray. 

A  second  very  small  body  of  soil  of  similar  character  occurs  on 
the  high  terraces  south  of  Coyote  Valley. 

Much  of  the  Corning  gravelly  clay  loam  is  in  a  high  state  of  cul- 
tivation, being  set  to  fruits  of  various  kinds  (PI.  IV,  fig.  2)  or  used 
in  the  production  of  truck  crops,  all  of  wdiich  do  w^ell.  A  part  of  it 
is  in  grain  and  a  part  is  yet  uncleared.    It  is  a  good  grain  soil. 


SOIL    SURVEY    OF    THE    UKIAH    AREA,    CALIFORNIA.  35 

Mechanical  analyses  of  samples  of  the  soil  and  sub-soil  follow: 
MccJiaiiical  aiialyscs  of  Corning  gravelly  clay  loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse      Medium 
sand.          sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

57304'3 

Soil 

Per  cent. 
3.5 
2.9 

Per  cent. 
6.8 
4.1 

Per  cent. 
3.4 
2.1 

Per  cent. 
12.5 
6.6 

Per  cent. 
12.2 
11.4 

Per  cent. 
34.1 
35.9 

Per  cent. 
27.4 

573047 

Subsoil 

37.1 

Pleasanton  Series. 

The  soils  of  the  Pleasanton  series  are  typically  brown,  wdth  varia- 
tions of  grayish  brown,  light  brown  or  dark  brown.  The  subsoils 
generally  are  heavier  than  the  surface  soils  and  more  compact  and 
lighter,  usually  a  yellowish  brown  or  grayish  broAvn.  The  subsoils 
are  underlain  typically  at  some  depth  less  than  6  feet  by  a  stratum 
of  open  to  rather  compact,  though  not  cemented,  gravel.  The  series 
is  derived  from  old  valley-filling  material  and  occupies  the  better 
drained  areas  of  terraces  and  benches. 

The  Pleasanton  series  is  distinguished  from  the  Pinole  series,  to 
which  it  is  closely  related  both  in  origin  and  in  occurrence,  by  its 
darker  colored  surface  soil. 

In  this  survey  the  Pleasanton  soils  depart  in  certain  characteris- 
tics from  the  series  as  developed  in  areas  previously  covered  by  the 
soil  survey.  The  surface  soils  are  somewhat  darker,  the  subsoil  is  not 
heavier  than  the  soil,  and  the  underlying  gravel  stratum  is  poorly 
developed  or  displaced  by  interbedded  strata  of  gravel,  sand,  silt, 
and  clay,  slightly  cemented  and  usually  of  various  shades  of  gray  or 
brown.  These  beds  show  that  they  were  deposited  in  water  which 
at  certain  stages  was  quiet. 

In  this  survey  only  one  member  of  this  series,  the  gravelly  loam,  is 
mapped.  There  are  a  very  few  small  areas  of  loam,  but  they  are  too 
small  to  be  shown  separately  on  the  map. 


PLEASANTON   GRAVELLY  LOAM. 


The  soil  of  the  Pleasanton  gravelly  loam  is  a  grayish-brown  to 
dark  grayish  brown  loam,  with  a  relatively  large  proportion  of 
gravel.  The  subsoil  encountered  below  a  depth  of  12  to  20  inches  is  a 
yellowish-gray  or  grayish-brown  loam,  several  shades  lighter  than 
the  surface  soil.  A  6-foot  section  of  the  soil  usually  shows  several 
changes  in  color,  texture,  and  quantity  of  gravel.  In  any  section 
there  are  layers  which  are  quite  gravelly  and  other  layers  nearly  free 
from  gravel,  and  the  gravelly  layers  may  occur  at  any  depth. 


36  FIELD   OPERATIONS   OF   THE   BUREAU   OF   SOILS,  1914. 

This  is  a  widely  distributed  type,  the  larger  and  more  important 
areas  occurring  north  and  south  of  Ukiah,  in  the  valley  of  Forsythe 
Creek,  near  Coyote  School,  and  along  Cold  Creek. 

The  topography  is  nearly  level  to  gently  sloping,  and  in  places, 
where  erosion  has  cut  back  into  the  edge  of  the  terrace,  gently 
rolling.  The  surface  is  in  general  smooth.  The  type  originally 
supported  a  forest  growth,  but  has  been  largely  cleared  for  farm- 
ing. It  is  used  for  the  production  of  grain,  to  which  it  is  only 
fairly  Avell  adapted,  the  yields  decreasing  after  a  few  years  cultiva- 
tion. The  soil  seems  well  adapted  to  grapes,  and  large  commercial 
plantings  have  been  made.  Other  fruits  probably  would  do  well. 
It  is  said  that  the  Pleasanton  gravelly  loam  is  better  suited  to  fruit 
than  the  closely  associated  Pinole  gravelly  loam. 

Pinole  Series. 

The  soils  of  the  Pinole  series  are  typically  pale  yellow  or  brownish 
yellow,  with  light  yellowish  brown  to  light  grayish  brown  variations. 
They  are  underlain  by  subsoils  of  similar  or  heavier  texture  but  of 
somewhat  lighter  yellow  or  gray  color.  At  varying  depths  below  6 
feet  occurs  a  stratum  consisting  of  interbedded  layers  of  clay,  silt, 
and  fine  sand,  and  some  of  gravel.  All  these  beds  are  slightly  ce- 
mented, and  seams  in  the  clay  and  silt  beds  have  a  coating  of  lime. 
The  color  of  this  substratum  varies  from  dull  yellow  to  light  brown, 
drab  or  gray. 

The  Pinole  soils  occupy  benches,  having  usually  a  smooth,  level  or 
gently  rolling  surface.  They  are  derived  from  old  valley-filling 
material.    They  were  originally  densely  forested. 

PINOLE    SANDY    LOAM. 

The  surface  soil  of  the  Pinole  sandy  loam  is  a  light  brownish  yel- 
low, light-yellow  or  yellowish-brown  sandy  loam,  about  1  to  2  feet  deep. 
This  is  underlain  by  a  yellow  or  brownish-yellow  loam  to  compact 
clay  loam  subsoil,  which  extends  to  a  depth  of  6  feet  or  more.  Where 
the  heavier  subsoil  occurs  near  the  surface  it  materially  affects  the 
agricultural  value  of  the  land  by  retarding  subsurface  or  internal 
drainage  and  root  development,  but  in  most  places  it  lies  below  a 
depth  of  6  feet,  which  is  deep  enough  to  allow  a  proper  growth  of 
grapevines  or  of  shallow-rooting  fruit  trees.  This  soil  has  a  small 
content  of  organic  matter. 

This  is  a  type  of  little  importance,  found  in  only  a  few  areas. 
One  high,  eroded  area  lies  in  the  western  part  of  Potter  Valley. 
Small  areas  lie  near  El  Poble.  northeast  of  Ukiah,  and  south  of 
Guidiville  at  Carrol  School.  A  larger  area  extends  south  and  east 
from  Guidiville. 


SOIL    SURVEY    OF    THE    UKIAH    AREA,    CALIFORNIA.  37 

The  topography  is  gently  sloping  or  rolling  to  rather  steep,  but 
the  surface  is  smooth.  Erosion  is  active  and  surface  drainage  is 
well  established.  The  area  in  Potter  Valley  is  in  pasture,  and  has  a 
tliin  covering  of  blue  oak.  The  other  areas  are  mainly  in  vineyards. 
Grapes,  and,  in  family  orchards,  apples,  peaches,  and  apricots,  give 
good  returns. 

In  a  gravelly  variation  of  this  type,  which  is  indicated  on  the  soil 
map  by  gravel  symbols,  the  soil  is  a  yellowish-gray  sandy  loam, 
containing  considerable  fine  gravel  about  the  size  of  a  pea.  The  sub- 
soil encountered  at  a  depth  of  about  3  feet  is  a  gravelly  sandy  loam. 
Only  one  area  of  this  variation  is  mapped.  This  occurs  in  McDowell 
A^alley,  where  it  occupies  the  main  part  of  the  floor  of  the  valley. 
The  surface  is  gently  sloping. 

This  area  is  devoted  to  general  farm  crops,  and  is  quite  produc- 
tive.   Grapes  are  grown  to  a  small  extent. 

PINOLE   LOAM. 

The  Pinole  loam  is  a  brownish-yellow  to  yellowish-brown  or  light 
grayish  brown  loam  about  2  feet  deep,  underlain  by  a  subsoil  of  the 
same  texture,  but  slightly  lighter  in  color.  Cobblestones  and  gravel 
are  scattered  through  soil  and  subsoil,  but  they  are  not  present  in 
sufficient  quantity  to  give  a  stony  or  gravelly  type.  The  substratum, 
characteristic  of  the  series,  is  encountered  at  depths  of  6  to  10  feet. 

The  areas  of  the  Pinole  loam  in  Potter  Valley  and  the  body  on  the 
east  side  of  Knights  Valley  are  largely  covered  with  grass,  with  a 
scattered  growth  of  trees,  and  in  this  regard  the  type  differs  from  the 
other  members  of  the  Pinole  series. 

This  type  is  of  small  extent.  One  area  occurs  at  the  head  of 
Eedwood  Valley,  and  another  along  Forsythe  Creek.  Several  areas 
occur  in  the  southeastern  part  of  Potter  Valley;  one  small  area  is 
encountered  near  Henry,  and  another  in  the  McDowell  Valley. 

The  type  occupies  low  hills  with  smooth  surfaces  and  has  a  gently 
rolling  topography.  It  is  well  drained.  The  soil  is  either  un- 
cleared or  is  used  for  pasture,  but  it  seems  probable  that  with  proper 
management  it  would  be  well  suited  to  fruits. 

Pinole  loam^  eroded  phase. — The  Pinole  loam,  eroded  phase,  is 
indicated  on  the  soil  map  by  cross-lining.  It  is  separated  from  the 
typical  soil  on  the  basis  of  difference  in  agricultural  value.  In  soil, 
subsoil,  and  substratum  it  is  very  similar  to  the  typical  soil,  differing 
only  in  that  the  surface  material  is  in  many  places  eroded  awa3% 
leaving  the  subsoil  or  substratum  exposed.  The  surface  is  so  steep 
and  hilly  that  cultivation  over  much  of  it  is  very  difficult  or  impos- 
sible. 

This  phase  lies  at  a  higher  level  than  the  areas  of  typical  soil,  and 
is  derived  from  older  alluvial-fan  deposits.     It  is  mapped  in  small 


38  FIELD    OPERATIONS    OF    THE    BUREAU    OF    SOILS,   1914. 

areas  adjoining  the  hills  in  the  southern  end  of  Potter  Valley  and 
in  an  area  of  moderate  extent  east  of  El  Roble.  It  is  not  farmed, 
but  supports  a  good  growth  of  timber. 

PINOLE  GRAV'ELLY  LOAM. 

The  soil  of  the  Pinole  gravelly  loam  is  a  brownish-yellow  or  light 
yellowish  brown  loam  about  2  feet  deep,  containing  a  large  percent- 
age of  gravel.  The  subsoil  is  very  similar  to  the  surface  soil  in 
texture  and  gravel  content,  but  the  color  is  generally  a  little  lighter, 
yellower,  and  grayer.  The  gravel  is  mainly  less  than  an  inch  in 
diameter  and  consists  largely  of  sandstone  and  metamorphosed  sand- 
stone and  shale  containing  seams  and  lenses  of  quartz.  The  gravel 
is  rather  unevenly  distributed,  in  places  2  or  3  times  as  much  as 
in  other  places,  but  nowhere  is  it  entirely  absent.  There  are  some 
large  cobbles  up  to  6  inches  in  diameter,  but  these  are  relatively  rare. 
The  type  is  not  markedly  leachy.  The  amount  of  organic  matter 
present  is  only  moderate.  The  type  is  underlain  at  depths  below  6 
feet  by  the  substratum  typical  of  the  Pinole  series.  Plate  V,  figure  1, 
shows  a  section  in  this  soil  near  Ukiah. 

Although  the  typical  color  of  the  Pinole  gravelly  loam  under  nor- 
mal conditions  is  prevailingly  as  described,  showing  dull  yellow 
rather  than  red  in  the  soil  and  subsoil,  there  are  places,  in  which  the 
soil  is  wet  during  the  rainy  season,  where  there  is  a  faint  pink  or 
red  color  in  the  subsoil. 

Slight  depressions  in  this  type  are  often  occupied  by  soil  which 
varies  from  the  typical  in  having  a  yellow  clay  loam  or  clay  subsoil. 
This  is  like  poorly  drained  phases  of  the  Tehama  soils,  but  the 
bodies  are  too  small  to  be  shown  separately  on  the  soil  map.  They 
are  very  inferior  to  the  main  portion  of  the  soil.  Drainage  is  very 
poor,  the  soil  appears  to  be  acid,  puddles  easily,  and  bakes.  It  is 
^aid,  however,  that  grapes  do  well  in  these  spots. 

The  Pinole  gravelly  loam  is  one  of  the  important  types  of  the 
survey  and  is  widely  distributed.  It  is  found  on  the  terraces  and 
benches  of  old  valley-filling  material  skirting  the  sides  of  the  valley 
and  occurs  in  disconnected  areas  from  the  northern  part  of  Redwood 
Valley  to  the  southern  part  of  Sanel  Valley.  It  occurs  also  in  Potter 
Valley,  in  McDowell  Valley,  and  in  several  of  the  small  valleys  of 
lateral  streariis.  In  places  the  type  has  a  terrace  topography,  and  in 
others  the  topography  of  old  alluvial  fans,  but  it  has  all  undei'gone 
erosion,  so  that  drainage  is  well  established.  The  topography  varies 
from  nearly  level  to  gently  sloping.  Much  of  this  type  is  well  suited 
to  irrigation,  if  water  can  be  supplied. 

At  present  the  Pinole  gravelly  loam  is  used  to  some  extent  for  pas- 
ture, vineyards,  and  grain  farming.    A  large  part  of  it  is  uncleared. 


SOIL   SURVEY   OF   THE   UKIAH   AEEA,   CALIFORNIA.  39 

For  pasturage,  hay  or  grain,  this  soil  is  only  moderately  productive. 
When  first  cleared,  it  gives  satisfactory  yields,  but  they  soon  decline. 
For  this  reason  many  farmers  consider  it  a  poor  soil,  but  it  is  well 
adapted  to  the  production  of  grapes,  and  many  commercial  vineyards 
have  been  set  out.  It  is  probabl}^  well  suited  to  other  fruits,  such  as 
apples,  prunes,  and  peaches,  but  there  are  no  bearing  commercial 
orchards  upon  it. 

Pinole  gravelly  loam,  eroded  phase. — The  Pinole  gravelly  loam, 
eroded  phase,  occupies  high-lying,  eroded  areas,  in  which  there  re- 
mains no  level  land.  It  forms  steep  hills,  and  has  a  much  lower 
agricultural  value  than  the  typical  areas,  as  cultivation  is  extremely 
difficult  and  expensive.  Very  little  development  has  been  attempted, 
except  in  smoother  parts,  w'here  dry-wine  grapes  are  grown  locally 
with  success  (PI.  Ill,  fig.  2). 

The  soil  profile  is  practically  the  same  as  that  of  the  typical  Pinole 
gravelly  loam,  except  that  the  surface  soil  is  in  many  places  eroded 
away,  exposing  the  subsoil  or  even  the  substratum. 

Large  areas  of  this  phase  are  found  on  the  old  alluvial  fans  of 
Forsythe  Creek  and  the  east  fork  of  the  Russian  river.  The  range 
of  hills  dividing  Coyote  Valley  and  the  narrow  Calpella  Valley  is 
occupied  by  this  soil.  A  large  area  lies  south  of  Coyote  Valley  and 
extends  along  the  east  side  of  the  main  valley  to  Ukiah.  Other  large 
areas  occur  farther  south  for  a  number  of  miles,  and  a  few  small 
areas  are  encountered  almost  as  far  south  as  Cummiskey.  The  phase 
occurs  also  in  Potter  Valley. 

The  Pinole  gravelly  loam,  eroded  phase,  is  practically  non- 
agricultural.  It  supports  a  fair  growth  of  oak,  fir,  and  madroiia  on 
favorable  slopes,  but  often  the  covering  consists  only  of  chamisal 
or  ceanothus. 

SOILS  DERIVED  FROM  RECENT  ALLUVIAL  DEPOSITS. 
Yolo  Series. 

The  Yolo  soils  are  brown,  with  variations  of  light  brown,  grayish 
brown  or  dark  brown,  and  with  subsoils  usually  of  the  same  texture 
or  of  somewhat  lighter  texture,  and  of  the  same  or  slightly  lighter 
color  than  the  surface  soil. 

These  soils  typically  occupy  gently  sloping  to  nearlj''  level  recent 
alluvial  fans  with  a  smooth  surface.  The  fans  are  steepest  where 
they  adjoin  the  hills,  the  outer  edges  being  more  nearly  level.  In 
this  survey  the  Yolo  soils  have  stream-bottom  or  river  flood  plain 
phases,  which  are  extensive  and  important. 

The  Yolo  soils  are  derived  from  recent  alluvial  deposits  having 
their  source  mainly  in  sedimentary  and  metamorphosed  sedimentary 
rocks.     Unlike  the  remnants  of  the  older  alluvial  fans  occupied  by 


40  FIELD   OPEEATIONS   OF    THE   BUREAU    OF   SOILS,   1914. 

the  older  valley-filling  material,  the  fans  ccfupied  by  the  Yolo  soils 
are  not  undergoing  erosion  and  removal,  but  are  being  built  up  by 
present  streams,  and  as  a  result  the  surface  has  a  more  uniform  slope. 
Yolo  soils  have  the  same  origin  as  the  Tehama  soils  from  Avhirh  they 
are  differentiated  on  the  basis  of  color,  being  darker  than  the 
Tehama.  Drainage  usually  is  well  established,  but  certain  parts  of 
the  fans  and  of  the  lower  lying  flood-plain  areas  are  subject  to  over- 
flow during  periods  of  flood.  In  this  survey  the  upper  subsoil 
usually  passes  into  a  deeper  subsoil  of  compact  gravelly  material  at 
depths  of  4  to  6  feet.  Valley  oak,  with  willow  along  the  streams, 
seems  to  have  been  the  predominating  tree  growth.  The  typical 
Yolo  soils  in  Potter  Valley  are  parklike  in  appearance,  with  a.  good 
growth  of  valley  oak  (see  PI.  I).  The  same  is  true  of  some  of  the 
smaller  fans  in  Ukiah  Valley.  In  Knights  Valley  the  valley  oak 
makes  a  particularly  good  growth.  Originally,  however,  there  was 
in  places  considerable  smaller  growth,  including  ceanothus,  poison 
oak,  and  some  manzanita.  The  stream-bottom  areas  were  originally 
forested  with  a  dense  growth  of  oak,  willow,  and  wild-grape  vines, 
with  some  ash  and  pepperwood. 

YOLO   FINE    SANDY   LOAM,    STREAM-BOTTOM   PHASE. 

The  surface  soil  of  the  stream-bottom  phase  of  the  Yolo  fine  sandy 
loam  is  a  light  grayish  brown  to  a  medium-brown  fine  sandy  loam.  It 
is  about  2  feet  deep,  and  grades  imperceptibly  into  a  subsoil  which  is 
very  similar  in  color  and  texture  to  the  surface  material.  This  is  a 
loose,  friable  soil,  very  easy  to  cultivate,  but  with  only  a  fair  supply 
of  organic  matter.  It  is  underlain  by  river  gravels,  but  almost 
invariably  these  are  found  below  the  depth  of  6  feet.  On  the  mar- 
gins of  some  areas  next  to  the  stream  this  soil  merges  into  Riverwash, 
and  parts  of  the  type  as  mapped  include  bars  and  strips  of  gravel  or 
sand  too  small  to  separate.  The  surface  of  this  type  when  quite  dry 
and  bleached  by  several  months  of  sunshine  often  appears  lighter  or 
grayer  than  it  does  under  normal  conditions. 

Areas  of  this  soil  are  distributed  throughout  the  survey  along  the 
Russian  River  and  the  East  Fork,  occupying  the  parts  of  the  river 
flood  plains  nearest  the  streams.  The  surface  is  level  or  is  marked  by 
long,  shallow  depressions,  which  are  abandoned  channels  of  the 
stream  or  are  caused  by  the  recent  eroding  action  of  floods.  The 
drainage,  owing  to  the  open,  loose  character  of  the  soil,  is  usually 
good,  but  in  depressions  it  may  be  poor  at  times  on  account  of  a  high 
water  table. 

The  soil  is,  for  the  most  part,  suitable  for  irrigation,  as  it  occupies 
a  low  position  near  the  river,  although  the  surface  in  places  is  un- 


SOIL   SURVEY   OF    THE   URIAH   AEEA,    CALIFORNIA. 


41 


favorable.  This  soil  is  one  of  the  most  valuable  in  the  area.  One  of 
the  most  profitable  pear  orchards  in  the  State  is  located  near  Hopland 
on  this  phase.  Little  of  the  soil,  however,  is  devoted  to  fruit.  Most 
of  it  is  used  for  the  production  of  hops  and  alfalfa,  to  which  it  is 
especially  well  suited.  (See  PI.  Ill,  fig.  1.)  A  small  part  of  the 
phase  is  used  for  grain  growing. 

As  mapped  in  this  area  the  phase  includes  small,  undifferentiated 
bodies  of  the  Yolo  fine  sand,  stream-bottom  phase,  which  are  too 
small  to  be  separated  satisfactorily.  The  soil  in  these  areas  is  a  light 
grayish  brown  fine  sand,  extending  to  depths  of  6  feet  or  more  with- 
out any  distinct  subsoil.  It  is  very  light  and  friable  and  easy  to 
cultivate.  It  has  a  low  percentage  of  organic  matter,  and  contains 
in  places  some  small,  rounded  gravel.  It  is  underlain  at  varying 
depths  by  river  gravels.  Small  areas  of  this  soil  occur  east  and  north 
of  Hopland,  near  the  Russian  River.  It  is  subject  to  periodic  over- 
flow, and  the  surface  is  marked  by  gentle  ridges  and  depressions 
resulting  from  flood  erosion.  Subdrainage  is  excessive.  The  pro- 
ductiveness of  this  soil  is  much  less  than  that  of  the  stream-bottom 
phase  of  the  fine  sandy  loam,  on  account  of  its  leachy  nature. 

Results  of  mechanical  analyses  of  samples  of  the  soil  and  subsoil 
follow : 

Mechanical  analyses  of  Yolo  fine  sandy  loam,  stream-bottom  phase. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

573028  

Son 

Per  cent. 

0.0 

.0 

Per  cent. 

0.2 

.0 

Per  cent. 

1.2 

.2 

Per  cent. 

23.0 

4,0 

Per  cent. 
41.4 
31.7 

Per  cent. 
27.2 
50.9 

Per  cent. 
6.9 

573029 

Subsoil 

13.4 

YOLO   LOAM. 


The  soil  of  the  Yolo  loam  is  a  dark-brown  or  dark  grayish  brown 
loam,  usually  containing  a  small  proportion  of  gravel.  It  is  friable, 
has  a  good  supply  of  organic  matter,  and  is  easily  cultivated.  The 
subsoil  is  encountered  at  depths  of  18  to  24  inches.  As  a  rule  it  is 
somewhat  lighter  in  color  than  the  surface  soil,  being  a  brown  or 
light  grayish  brown  or,  in  the  lower  depths,  yellowish  brown.  It 
consists  of  a  loam,  but  usually  contains  more  gravel  than  the  surface 
soil,  and  the  percentage  of  gravel  increases  and  the  material  be- 
comes more  compact  with  depth. 

Large  areas  of  the  Yolo  loam  occur  in  Potter  Valley,  and  smaller 
areas  are  found  near  Ukiah  and  farther  south  in  the  survey.  The 
areas  are  gently  sloping  to  nearly  flat,  with  a  smooth  surface  marked 


42 


FIELD   OPERATIONS   OF   THE   BUREAU   OF   SOILS,  1914. 


only  by  occasional  shifting  channels  of  intermittent  streams.  Drain- 
age is  usually  good,  though  there  are  a  few  poorly  drained  depres- 
sions. The  type  is  well  suited  to  irrigation  on  account  of  its  smooth 
surface  and  gentle  slope,  and  water  for  irrigation  could  probably  be 
obtained. 

At  present  the  Yolo  loam  is  mainly  in  grain,  of  which  satisfactory 
yields  are  obtained.  Alfalfa  is  grown  in  a  small  way;  it  can  be 
produced  successfully  without  irrigation.  The  type  is  well  suited 
to  fruit,  although  very  little  is  grown.  In  Potter  Valley  some  pear 
trees,  over  50  years  old,  are  healthy  and  bear  regularly.  This  type 
constitutes  good  general-farming  land. 

Yolo  loam,  stream-hottoTn  phase. — The  soil  of  the  stream-bottom 
phase  of  the  Yolo  loam  is  a  grayish -brown  or  brown  loam  about  2 
feet  deep.  It  contains  some  gravel,  but  is  friable  and  is  easil}'  culti- 
vated. It  is  underlain  by  a  subsoil  of  the  same  color  and  texture, 
but  usually  containing  more  gravel. 

This  phase  is  of  small  extent.  One  area  occurs  south  of  Hopland 
and  another  north  of  El  Roble.  The  surface  is  level  or  gently  un- 
dulating and  is  subject  to  some  erosion  and  overflow  during  flood 
stages  of  the  Russian  River.  The  subdrainage  is  good.  The  soil  is 
not  very  uniform  and  varies  considerably  in  agricultural  value.  It 
is  mainly  in  grain  and  alfalfa. 

Below  are  given  the  results  of  mechanical  analyses  of  samples  of 
the  soil  and  subsoil  of  the  typical  Yolo  loam  and  of  the  stream-bottom 
phase : 

Mechanical  analyses  of  Yolo  loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

sut. 

Clay. 

Typical: 

573020 

Soil 

Per  cent. 
1.0 
1.2 

5.2 
3.1 

Per  cent. 
2.0 
2.9 

5.4 
4.9 

Per  cent. 
2.0 
3.0 

2.6 
3.0 

Per  cent. 
15.6 
24.7 

11.4 
13.0 

Per  cent. 
20.7 
22.6 

16.4 
18.4 

Per  cent. 
37.9 
29.5 

39.7 
34.7 

Per  cent. 
20.7 

573021 

Stream  -  bottom 
phase: 
573037    

.Subsoil 

Soil...-. 

16.2 
19.6 

573038 

Subsoil 

22.6 

YOLO    GKAVEIXY    LOAM. 


The  Yolo  gravelly  loam  is  indicated  on  the  soil  map  by  gravel  sym- 
bols in  the  Yolo  loam  color.  The  soil  is  a  dark  grayish  brown  loam, 
containing  enough  gravel  to  affect  its  texture  and  structure  and  cul- 
tural requirements.  The  gravel  consists  of  small,  rounded  pebbles 
of  a  variety  of  rocks.  The  subsoil  is  encountered  at  depths  of  18  to 
24  inches.    It  usually  is  somewhat  lighter  in  color  than  the  surface 


SOIL   SURVEY   OF   THE    UKIAH   AREA,    CALIFORNIA.  43 

soil,  being  brown  or  light  grayish  brown,  often  yellowish  brown  in 
the  lower  part.  It  consists  of  a  gravelly  loam,  generally  containing 
more  gravel  than  the  surface  soil,  and  becomes  very  compact  at  lower 
depths.  The  type  is  easil}^  cultivated,  has  a  good  supply  of  organic 
matter,  and  retains  moisture  well. 

Large  areas  of  the  Yolo  gravelly  loam  are  found  in  Potter  Valley 
and  on  the  east  side  of  Ukiah  Valley,  and  smaller  areas  are  well 
distributed  throughout  the  survey.  In  many  cases  it  occurs  on  the 
upper  parts  of  the  small  fans,  the  heavier  members  of  the  same  series 
bordering  it  on  the  lower  side.  The  large  areas  of  the  gravelly  loam 
on  the  east  side  of  Ukiah  Valley,  however,  extend  to  the  flood  plain 
of  the  Russian  River.  The  topography  is  gently  sloping,  and  the 
surface  is  smooth.  Drainage  is  well  developed.  This  type  is  well 
suited  to  irrigation.  Most  of  it  is  in  grain,  and  yields  are  fair  to 
good,  though  lower  than  on  the  stream-bottom  soils.  Very  little  fruit 
is  grown,  but  the  type  seems  well  suited  to  grapes,  prunes,  and  other 
fruits.  Corn  is  grown  extensively.  This  is  a  good  soil  for  general 
farming. 

Yolo  gravelly  loaTn^  streaTn-hottom  'phase. — The  Yolo  gravelly 
loam,  stream-bottom  phase,  is  indicated  on  the  map  by  gravel  sym- 
bols and  cross  lines  in  the  Yolo  loam  color.  The  surface  soil  is  a 
light  grayish  brown  or  light-browH  to  dark-brown  gravelly  loam, 
from  1  to  3  feet  deep.  This  is  underlain  by  a  subsoil  of  the  same 
color,  but  generally  containing  more  gravel.  This  phase  is  quite 
variable  and  includes  small  areas  with  little  gravel,  small  areas  of 
clay  loam,  some  fine  sandy  loam,  and  in  places  small  bodies  of 
Riverwash.  These  variations  are  too  inextensive  to  be  indicated  on 
the  soil  map. 

This  phase,  which  has  a  small  total  area,  is  found  in  small  bodies 
distributed  throughout  the  area.  It  occurs  on  the  flood  plains  of 
the  small  tributaries  of  the  Russian  River  and  in  the  main  valley 
where  large  tributaries  of  this  river  enter.  The  largest  area  occurs 
just  south  of  Hopland.  The  surface  is  level  or  is  marked  by  shallow 
abandoned  stream  channels.  The  streams  which  have  formed  these 
bodies  are  likely  at  any  time  to  encroach  on  them,  as  their  channels 
are  continually  shifting.  The  areas  are  subject  to  periodic  overflow; 
otherwise  the  drainage  is  fairly  good. 

•  Grain,  alfalfa,  and  grapes  are  grown  on  this  phase.  It  also  affords 
some  pasturage.  The  different  areas  vary  widely  in  agricultural 
value,  owing  to  variations  in  texture,  depth  to  gravel  beds,  and  confli- 
tions  of  overflow.  The  better  areas  are  practically  as  good  as  the 
stream-bottom  phase  of  the  fine  sandy  loam  of  the  series. 


44 


FIELD  OPERATIONS   OF   THE  BUREAU   OF   SOILS,  1914. 


Kesults  of  mechanical  analyses  of  samples  of  the  soil  and  subsoil 
of  the  typical  Yolo  gravelly  loam  follow : 

Mechanical  analyses  of  Yolo  gravelly  loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

573012 

Soil 

Per  cent. 
1.6 
2,5 

Per  cent. 
1.6 
4.2 

Per  cent. 
1.2 
3.0 

Per  cent. 
10.2 
14.6 

Per  cent. 
18.1 
18.4 

Per  cent. 
47.6 
37.2 

Per  cent. 
19.2 

573013 

Subsoil 

19.9 

YOLO    SILT   LOAM. 


The  soil  of  the  Yolo  silt  loam  is  a  dark  grayish  brown  to  dark- 
brown  silt  loam  about  18  inches  deep.  This  passes  gradually  into  a 
subsoil  of  the  same  color  and  usually  clay  loam  texture.  The  soil  is 
rather  friable,  contains  a  good  supply  of  organic  matter,  is  retentive  of 
moisture,  and  is  easily  cultivated. 

Large  areas  of  this  type  are  found  in  Potter  Valley,  an  area  of 
some  size  is  located  at  Ukiah,  and  a  fair-sized  area  in  Knights  Valley. 
In  Potter  Valley  and  Knights  Valley  the  type  comprises  a  large  part 
of  the  basin  in  the  center  of  the  valley.  The  surface  is  nearly  level 
and  in  general  smooth.  The  type  is  well  suited  to  irrigation,  both  on 
account  of  its  low  position  and  character  of  surface. 

The  Yolo  silt  loam  is  a  productive,  highly  prized  soil,  well  suited 
to  a  wide  range  of  crops.  Most  of  it  is  devoted  to  the  production  of 
grain.  There  are  a  few  hop  fields  in  Potter  Valley.  The  soil  is  well 
suited  to  alfalfa,  and  this  crop  is  grown  extensively. 

Yolo  silt  loam.,  stream-bottom  phase. — The  soil  of  the  stream-bot- 
tom phase  of  the  Yolo  silt  loam,  which  is  indicated  upon  the  soil  map 
by  crosslines  over  the  Yolo  silt  loam  color,  is  a  brown  or  dark-brown 
silt  loam  1  to  2  feet  deep.  The  subsoil  is  similar  to  the  surface  soil, 
but  usually  somewhat  lighter  in  color.  In  a  few  places  a  compact  or 
I)artially  cemented  stratum  is  encountered  at  depths  of  4  or  5  feet. 
Occasionally  near  the  bluffs  or  in  slight  depressions  the  type  has  a 
siltv  clay  loam  subsoil.  In  places  some  iron  concretions  about  the  size 
of  buckshot  are  present,  and  in  poorly  drained  spots  the  subsoil  is 
sometimes  stained  with  iron.  The  color  of  the  surface  when  quite 
dry  is  often  light  grayish  brown.  The  type  is  loose  and  friable  in. 
structure,  is  easily  cultivated,  and  has  a  good  supply  of  organic 
matter. 

This  is  one  of  the  most  important  and  valuable  soils  in  the  area. 
It  is  distributed  through  the  flood  plain  of  the  Russian  River,  in 
places  occupying  the  entire  plain  though  in  others  it  adjoins  the  bor- 
dering bluffs  and  is  separated  from  the  river  by  the  stream-bottom 
phase  of  the  Yolo  fine  sandy  loam.     The  type  is  level  and  smooth, 


SOIL   SURVEY   OF    THE   UKIAH   AREA,    CALIEORNIA, 


45 


and  is  well  suited  to  irrigation.  Drainage  is  almost  invariably  good, 
except  during  annual  overflows. 

The  Yolo  silt  loam,  stream-bottom  phase  is  in  a  high  state  of  culti- 
vation. Many  hop  fields  are  found  on  it  and  alfalfa  also  is  grown 
extensively.  Grain  is  grown  in  a  few  places,  but  the  soil  gives  so 
much  larger  returns  when  devoted  to  other  crops  that  the  acreage  in 
grain  is  steadily  decreasing.  The  most  successful  orchards  of  prunes 
and  pears  near  Ukiah  are  found  on  this  phase.  It  seems  well  suited  to 
both  these  fruits.  There  is  a  home  orchard  of  apples  over  60  ye9,rs 
old  on  this  soil  in  Redwood  Valley,  which  is  very  thrifty  and  bears 
regularly. 

Results  of  mechanical  'analyses  of  samples  of  soil  and  subsoil  of  the 
stream-bottom  phase  follow : 

Mechanical  analyses  of  Tolo  silt  loam,  stream-bottom  phase. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

573016 

Soil 

Per  cent. 

0.0 

.2 

Per  cent. 

0.2 

.8 

Per  cent. 

0.2 

.6 

Per  cent. 
3.0 
4.5 

Per  cent. 
13.5 
21.0 

Per  cent. 
62.0 
48.6 

Per  cent. 
21.3 

573017 

Subsoil 

24.2 

YOLO   SILTY  CLAY  LOAlSf. 


The  soil  of  the  Yolo  silty  clay  loam  is  a  brown  silty  clay  loam, 
obout  18  inches  deep,  passing  gradually  into  a  subsoil  of  the  same 
color  and  of  the  same  or  slightly  heavier  texture.  The  soil  is  com- 
pact, and  its  cultivation  difficult,  the  soil  clodding  if  plowed  when  wet. 
It  contains  a  good  supply  of  organic  matter.  There  are  often  thin 
beds  of  gravel  or  strata  of  material  of  lighter  texture  in  the  subsoil. 

This  is  a  type  of  minor  extent.  It  occurs  in  small  areas  well 
distributed  throughout  the  survey,  occupjdng  depressions  or  poorly 
drained  spots  surrounded  by  lighter  members  of  the  same  series. 
The  surface  is  level  or  basinlike  and  smooth.  The  type  is  not  sub- 
ject to  erosion.  Drainage  is  often  poor.  This  type  is  in  grain  and 
pasture.     Crop  yields  are  generally  good. 

Yolo  silty  clay  loam,  stream-bottom  phase. — The  Yolo  silty  clay 
loam,  stream-bottom  phase,  is  indicated  on  the  soil  map  by  cross- 
lines  on  the  Yolo  silty  clay  loam  color.  The  soil  is  a  brown  to  dark 
grayish  brown,  or  dark-brown  silty  clay  loam,  from  1  to  2  feet  deep. 
The  subsoil  is  brown  to  dark  brown  in  color  and  may  be  mottled  in 
places  with  brown  iron  stains.  It  consists  of  a  silty  clay  loam  to 
silty  clay.  The  structure  of  the  soil  is  rather  dense,  and  the  soil 
when  wet  is  sticky  and  has  a  tendency  to  clod,  making  cultivation 
difficult  except  under  proper  moisture  conditions.  The  soil  has  a 
good  supply  of  organic  matter. 


46 


FIELD   OPERATIONS   OF    THE   BUREAU    OF   SOILS,   1914. 


This  is  a  much  less  extensive  soil  than  the  stream-bottom  phase 
of  the  Yolo  silt  loam,  Avith  Avhich  it  is  associated.  It  occupies  basins 
or  depressions  within  the  larger  areas  of  the  silt  loam,  evidently 
where  the  movement  of  the  water  is  slow  and  the  clay  has  oppor- 
tunity to  settle.  It  is  mapped  in  a  few  small  areas  near  Ukiah.  It 
occurs  also  in  a  number  of  strips  too  small  to  be  shown  separately 
on  the  map.  In  grain  fields  in  the  spring  the  white  meadow  foam 
is  very  abundant,  and  this  growth  largely  distinguishes  the  areas  of 
this  type  from  the  adjoining  stream-bottom  phase  of  the  Yolo  silt 
loam.  The  surface  is  level  and  smooth.  Drainage  is  fair  to  poor. 
The  areas  are  Avell  adapted  to  irrigation. 

This  phase  is  used  for  the  same  crops  as  the  adjoining  silt  loam. 
It  occurs  in  such  small  areas  that  its  crop  adaptation  has  not  been 
definitely  determined,  though  it  apparently  is  not  so  well  suited  to 
hops  as  is  the  silt  loam.  It  seems  well  suited  to  alfalfa  where  the 
drainage  is  adequate.  One  pear  orchard,  situated  both  on  this 
phase  and  on  the  silt  loam,  gives  better  returns  on  the  heavier 
type.  A  large  part  of  the  phase  is  in  grain.  It  is  a  very  rich, 
productive  soil. 

The  following  table  gives  the  results  of  mechanical  analyses  of 
samples  of  the  soil  and  subsoil  of  the  typical  Yolo  silty  clay  loam 
and  of  the  stream-bottom  phase: 

Mechanical  analyses  of  Yolo  silty  clay   loam. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

(^lay. 

Typical: 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

573018 ,. 

Soil 

1.0 

1.7 

2.6 
3.2 

1.7 
2.2 

8.3 
11.3 

14.2 
14.1 

47.4 
44.6 

24.6 

573019 

ouhsoil 

23.0 

Stream  -  bottom 

phase: 

573014 

Soil 

.1 

.2 

.2 

1.4 

5.2 

65.5 

27.4 

573015  

Subsoil 

.6 

2.2 

1.8 

7.4 

13.4 

46.4 

28.6 

Tehama  Series. 


The  Tehama  soils  are  prevailingly  grayish  yellow  or  brownish 
yellow.  They  occupy  recent  gently  sloping  to  nearly  level,  smooth 
alluvial  fans  formed  by  intermittent  streams.  The  material  is  de- 
rived from  a  variety  of  rocks,  in  the  Ukiah  area  apparently  coming 
largely  from  sedimentary  and  metamorphosed  sedimentary  rocks. 

The  Tehjima  soils  are  similar  in  mode  of  formation  to  the  Yolo 
soils,  but  differ  from  the  latter  in  being  lighter  in  color,  a  difference 
due  in  part  to  a  smaller  admixture  of  organic  matter  and  in  part 
to  a  difference  in  the  soil  materials. 


SOIL   SURVEY   OF   THE   UKIAH   AREA,   CALIFORNIA.  47 

The  native  vegetation  is  valley  oak,  with  willow  along  the  stream 
courses,  the  growth  being  scattering.  Most  of  the  native  covering 
has  been  removed. 

TEHAMA  LOAM. 

The  soil  of  the  Tehama  loam  is  a  light  yellowish  brown  or  light 
grayish  brown  loam  about  2  feet  deep,  apparently  low  in  organic 
matter.  The  subsoil  is  slightly  lighter  in  color,  being  yellowish 
brown  or  brownish  yellow,  and  consists  of  a  loam  or  a  clay.  Some 
small,  rounded  gravel  is  scattered  through  both  soil  and  subsoil. 
The  soil  is  evidently  mildly  acid. 

Small  areas  of  this  type  are  scattered  throughout  the  survey. 
They  have  a  gently  sloping,  smooth  surface  and  may  be  subject  to 
erosion  in  places.  Drainage  i§  good,  except  in  the  area  at  Old 
Hopland. 

This  type  is  mainly  in  grain,  to  which  it  seems  well  adapted. 
Fruit  also  does  well. 

TEHAMA    GRAVELLY    LOAM. 

The  soil  of  the  Tehama  gravelly  loam,  which  is  indicated  on  the 
soil  map  by  gravel  symbols  over  the  Tehama  loam  color,  is  a  light 
yellowish  brown  or  light  grayish  brown  loam,  carrying  large  quanti- 
ties of  gravel.  It  varies  from  18  to  30  inches  in  depth.  This  soil 
has  a  friable  structure  and  is  easy  to  cultivate.  It  contains  a  rela- 
tively small  quantity  of  organic  matter.  The  subsoil  is  light  yellow 
or  yellowish  brown  to  grayish  brown  and  is  often  mottled  with 
gray.     It  is  a  gravelly  loam  to  a  gravelly  clay  loam  in  texture. 

Small  areas  of  this  type  are  found  well  distributed  throughout 
the  survey,  generally  occurring  well  back  against  the  hills  at  the 
edge  of  the  valley.  The  type  is  gently  sloping  and  has  a  smooth 
surface.  Erosion  as  a  rule  is  not  active.  The  drainage  is  good,  ex- 
cept in  some  shallow  sloughs.  The  type  is  fairly  well  suited  to 
irrigation. 

This  soil  is  mainly  in  grain,  but  some  fruit  has  been  set  out  in 
places.     Apparently  it  is  well  adapted  to  fruit  culture. 

TEHAMA   SILT  LOAM,   POORLY  DRAINED  PHASE. 

The  soil  of  the  Tehama  silt  loam,  poorly  drained  phase,  is  a  light - 
gray  to  grayish-yellow  silt  loam,  with  low  organic-matter  content 
and  about  2  feet  deep.  The  subsoil  is  a  light-yellow  or  yellow  mot- 
tled with  gray  clay  loam.  The  soil  and  subsoil  often  have  rusty  iron 
stains.  The  soil  is  sticky  and  difficult  to  cultivate.  It  is  apparently 
slightly  acid. 

Two  small  areas  of  this  soil  are  found  in  the  western  part  of  Potter 
Valley.    They  are  level,  have  a  smooth  surface,  and  occupy  poorly 


48  FIELD   OPERATIONS   OF    THE   BUREAU   OF   SOILS,   1914. 

drained  depressions.  They  are  used  for  pasture  and  the  production 
of  grain.  One  of  the  areas  has  considerable  salt  grass,  indicating  the 
presence  of  alkali.  This  is  the  only  indication  of  alkali  in  the  survey. 
One  small  area  is  mapped  in  the  Calpella  Valley,  across  the  river 
from  and  east  of  Calpella.  It  occupies  a  bench  some  distance  above 
the  river  and  apparently  consists  of  recent  alluvial-fan  material,  de- 
rived from  the  Pinole  soils.  It  has  a  sloping  surface  and  is  mainly 
uncleared. 

Because  of  their  small  extent  a  few  small  areas  of  Tehama  fine 
sandy  loam,  poorly  drained  phase,  north  of  Ukiah  are  included  with 
the  poorly  drained  phase  of  the  silt  loam  type.  The  soil  ranges 
from  1  to  2  feet  in  depth  and  is  underlain  by  a  loam  to  clay  loam 
subsoil,  which  is  light  yellow,  mottled  with  gray.  Both  soil  and 
subsoil  contain  some  small,  rounded  gravel,  but  not  enough  to  affect 
the  texture. 

A  part  of  the  fine  sandy  loam  type  is  in  grain  and  a  part  in  vine- 
yards, and  the  remainder  is  being  set  to  prunes  and  pears. 

HoNCUT  Series. 

The  surface  soils  of  the  Honcut  series,  as  recognized  in  previous 
surveys,  are  brown  to  reddish  brown  in  color,  and  the  subsoils  gener- 
ally similar  to  the  surface  soil  in  color,  texture,  and  structure.  They 
consist  of  recent  alluvial-fan  deposits,  with  phases  occupying  flood 
plains  or  lower  terraces.  The  soil  materials  are  derived  from  a  wide 
variety  of  rocks,  though  largely  from  quartz-free  igneous  and  meta- 
morphic  or  altered  basic  igneous  rocks. 

In  this  survey  only  small  areas  of  a  red  phase  of  this  series  are 
mapped.  These,  owing  to  their  departure  from  the  typical  Honcut 
soils  in  color,  would,  if  more  extensive,  be  classified  in  a  new  series. 
The  soil  is  brownish  red  to  rusty  red  or  dark  red  in  color,  and  is 
underlain  by  a  subsoil  of  the  same  color  but  usually  of  heavier  texture. 
The  topography  is  gently  sloping  to  nearly  level,  and  the  surface  is 
smooth.  These  small  areas  form  local  alluvial-fan  deposits  of  ma- 
terial eroded  from  areas  of  the  Aiken  soils.  They  were  originally 
covered  with  a  good  growth  of  fir,  oak,  and  smaller  plants,  prac- 
tically all  of  which  have  been  removed. 

HONCUT    LOAM,    KEO    PHASE. 

The  surface  soil  of  the  Honcut  loam,  red  phase,  is  a  yellowish-red 
or  dark-red  loam  about  2  feet  deep.  li  is  friable  and  is  easily  culti- 
vated, and  contains  a  fair  percentage  of  organic  matter.  The  subsoil 
is  of  the  same  color,  a  clay  loam  in  texture,  and  usually  passes  into 
very  compact  material  at  depths  less  than  6  feet.  Both  soil  and  sub- 
soil contain  small  quantities  of  subangiilar  to  rounded  gravel. 


SOIL   SURVEY    OF    THE   URIAH   AREA,   CALIFORNIA. 


49 


This  type  is  mapped  in  a  few  small  areas  in  the  southern  and  cen- 
tral parts  of  the  survey,  forming  small  fans  at  the  base  of  the  hills 
bordering  the  valley.  The  surface  is  sloping  and  smooth,  though  in 
places  subject  to  erosion.    Drainage  is  good. 

The  Honcut  loam,  red  phase,  is  a  productive  soil.  It  has  been  used 
for  the  production  of  grain,  but  vineyards  and  orchards  are  being 
set  out.    It  seems  well  suited  to  fruit  growing. 

HONCUT    GRAVELLY    LOAM,    BED    PHASE. 

The  soil  of  the  Honcut  gravelly  loam,  red  phase,  is  a  dark-red  or 
brownish-red  loam,  containing  considerable  small,  angular  to  rounded 
gravel.  It  is  from  18  to  24  inches  deep,  is  friable  and  easy  to  culti- 
vate, and  contains  a  fair  percentage  of  organic  matter.  The  sub- 
soil, a  gravelly  clay  loam,  becoming  very  compact  in  the  lower  part, 
is  very  similar  to  the  soil  in  color.  This  soil  is  indicated  upon  the 
soil  map  by  gravel  symbols  in  the  Honcut  loam  color. 

Several  small  areas  of  this  phase  are  mapped  near  Hopland.  They 
are  sloping,  have  a  smooth  surface,  and  are  well  drained.  Erosion  is 
active  in  places.  Grain,  orchard  fruits,  and  grapes  are  produced. 
The  type  is  quite  productive  and  is  apparently  well  suited  to  fruit 
growdng. 

Below  are  given  the  results  of  mechanical  analyses  of  samples  of 
the  soil  and  sul;)soil  of  the  Honcut  gravelly  loam,  red  phase : 

Mechanical  analyses  of  Honcut  gravelly  loam,  red  phase. 


Number. 

Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

573054        

Soil 

Per  cent. 
5.4 
11.0 

Per  cent. 
6.6 
17.6 

Per  cent. 
3.8 
9.4 

Per  cent. 
10.9 
17.2 

Per  cent. 
9.4 
5.8 

Per  cent. 
43.2 
14.8 

Per  cent. 
20.9 

573055 

Subsoil 

24.2 

Dublin  Series. 

The  soils  of  the  Dublin  series  are  dark  gray  to  black.  The  subsoil 
is  dull  yellow  to  yellowish  brown  or  grayish  brown  in  color  and 
usually  lighter  in  texture  than  the  surface  soil.  There  is,  however, 
little  uniformity  either  in  the  color  or  texture  of  the  subsoil  and  sub- 
stratum, which  consist  of  alternate  layers  of  clay,  silt,  and  loam, 
with  an  occasional  bed  of  gravel  at  lower  dej^ths. 

The  surface  of  these  soils  is  nearly  level  and  smooth.  A  few  areas 
fiave  a  gently  sloping  surface.  The  native  vegetation,  which  has 
nearly  all  been  removed,  consisted  of  oak  and  willow,  with  some  un- 
derbrush. 


50  FIELD   OPERATIONS   OF   THE   BUREAU   OF   SOILS,  1914. 

The  Dublin  soil  occurs  typically  on  alluvial  fans,  and,  as  mapped 
in  this  survey,  many  of  the  areas,  especially  those  in  Potter  Valley, 
occupy  low,  broad  basins  which  have  only  recently  been  drained. 
They  occur  in  the  extreme  outer  edge  of  the  low,  broad  fans  and  differ 
in  their  topography  and  drainage  from  areas  of  the  other  alluvial-fan 
soils.  The  soil  evidently  owes  its  black  color  to  the  high  organic  mat- 
ter and  lime  content.  This  dark  color  distinguishes  the  series  from 
the  other  water-laid  soils  of  the  area. 

DUBLIN  CLAY. 

The  surface  soil  of  the  Dublin  clay  is  a  dark-gray  to  black  clay 
from  1^  to  4  feet  deep,  carrying  much  organic  matter,  heavy  and 
sticky  when  wet,  and  inclined  to  crack  when  dry.  The  subsoil  is 
lighter  in  color  than  the  soil,  being  brown,  gray  or  yellowish  gray.  It 
varies  in  texture  from  a  clay  loam  to  clay  and  in  places  contains  layers 
of  gravelly  material.  Strata  differing  in  color  and  texture  are  en- 
countered at  varying  depths,  and  as  the  lower  depths  are  reached  the 
gravel  content  increases.  The  color  of  the  Dublin  clay  when  dry  and 
powdered  is  considerably  lighter  than  under  normal  moisture  condi- 
tions. In  a  few  places  the  soil  is  stained  with  iron  and  has  a  rusty 
color  and  is  mottled  with  light  gray  or  yellow.  It  is  a  very  difficult 
soil  to  cultivate,  forming  clods  unless  plowed  and  cultivated  under 
proper  moisture  conditions. 

The  areas  of  this  type  are  level  or  basinlike  and  in  one  case  gently 
sloping.  Several  areas  are  mapped  in  Potter  Valley.  Here  the  soil 
occupies  shallow  basins.  A  small  area  occurs  on  the  lands  of  the 
Mendocino  State  Hospital  near  Ukiah.  In  this  case  the  type  occupies 
a  small  basin  which  has  been  formed  by  the  building  out  of  the  fan 
of  the  stream  just  south  of  it.  The  soil  in  this  case  is  not  uniformly 
a  clay,  ranging  in  texture  from  loam  to  clay.  The  small  area  about 
1^  miles  north  of  Hopland  is  gently  sloping,  occupying  a  low  fan. 
The  surface  is  smooth,  erosion  is  not  active,  and  drainage  is  generally 
poor.  The  area  on  the  farm  of  the  Mendocino  State  Hospital  is 
drained  artificially. 

This  soil  is  well  suited  to  irrigation.  A  part  of  it  is  uncleared 
and  is  used  for  pasture.  Grain  is  the  principal  crop  on  the  cleared 
areas.    Some  alfalfa  is  grown  and  does  very  well. 


SOIL   SUKVEY   OF    THE   UKIAH   AEEA,   OALIFOBXIA. 


51 


The  following  table  gives  the  results  of  mechanical  analyses  of 
samples  of  they  soil,  subsoil,  and  lower  subsoil  of  the  Dublin  clay : 

Mechanical   analyses  of  Dublin  clay. 


Number.          Description. 

Fine 
gravel. 

Coarse 
sand. 

Medium 
sand. 

Fine 
sand. 

Very  fine 
sand. 

Silt. 

Clay. 

573034 Soil 

Per  cent. 
0.2 
7.2 
2.4 

Per  cent. 
0.8 
9.0 
2.4 

Per  cent. 
0.8 
4.7 
1.0 

Per  cent. 
6.2 
18.9 
4.2 

Per  cent. 
10.4 
18.6 
6.4 

Per  cent. 
48.4 
27.7 
45.8 

Per  cent. 
33.4 

573035 Subsoil 

573036 Lower  sub- 

1      soil. 

13.7 
37.7 

Miscellaneous   Material. 


BIVEBWASH. 


Riverwash  consists  of  the  sands  and  gravels  in  low-lying,  flood- 
swept  areas  along  the  Russian  River  and  some  of  its  tributaries. 
For  the  most  part,  Riverwa.sh  is  devoid  of  vegetation,  but  in  places 
there  is  a  growth  of  willow,  cottonwood,  and  many  annual  weeds. 
The  land  is  nonagricultural  on  account  of  its  topographic  position 
and  its  coarse  texture  and  leachy  nature. 

SUMMARY. 


The  Ukiah  area  comprises  the  valleys  of  the  Russian  River  and 
its  large  tributaries  within  Mendocino  County,  Cal.  The  sur- 
vey covers  an  area  of  303  square  miles,  or  193,920  acres.  It 
includes  several  arable  valleys  and  a  part  of  the  Coast  Range  Moun- 
tains.   The  entire  drainage  is  through  the  Russian  River  system. 

The  Ukiah  area  was  settled  between  1850  and  1860,  the  settlers 
coming  largeh'  from  the  southeastern  part  of  the  United  States. 
The  townships  of  Potter  Valley,  Ukiah,  and  Sanel,  which  approxi- 
mately conform  with  the  area  surveyed,  have  a  population  of  6,587, 
according  to  the  1910  census.  The  population  is  predominantly 
Anglo-Saxon,  and  is  confined  mainly  to  the  arable  valleys,  the 
settlement  of  the  hill  regions  being  sparse.  Ukiah  with  a  popula- 
tion of  something  over  2,000  is  the  principal  town  in  the  area.  Other 
towns  are  of  local  importance  as  trading  centers  in  the  various 
valleys. 

Transportation  facilities  are  furnished  by  the  Northwestern 
Pacific  Railroad.  A  good  system  of  roads  reaches  all  the  arable  sec- 
tions. All  the  grain  and  hay  produced  are  sold  within  the  area ;  the 
live  stock,  hops,  and  fruit  are  mainly  shipped  southward  to  the  Bay 
rem  on. 


52  FIELD  OPERATIONS  OF   THE  BUEEAU   OF   SOILS,  1914. 

The  climate  is  mild  and  is  well  suited  to  the  production  of  general 
farm  crops,  alfalfa,  hops,  grapes,  and  most  tree  and  bush  irmtv. 
The  Weather  Bureau  station  at  Ukiah  reports  the  mean  annual 
temperature  as  57.6°  F.  and  the  mean  annual  precipitation  as  37.8 
inches. 

In  the  early  historj^  of  this  region  stock  raising  was  the  lead- 
ing agricultural  interest,  hay  and  most  of  the  grain  pro- 
duced being  used  for  feed.  At  present  sheep  and  cattle  are  raised 
in  large  numbers  on  the  rolling  hills  bordering  the  arable  valleys. 
A  large  number  of  hogs  and  horses  also  are  raised.  Hops  constitute 
one  of  the  main  crops.  Wheat  is  the  principal  grain  crop,  closely 
followed  by  oats,  while  barley  and  corn  are  grown  to  a  smaller  ex- 
tent. Grapes  for  wine  making  are  grown  extensively,  and  the  pro- 
duction of  fruit,  although  less  important  than  in  regions  to  the 
south,  is  receiving  increasing  attention.  Alfalfa  is  a  comparatively 
new  crop,  but  is  rapidly  gaining  in  favor.  Irrigation  is  receiving 
some  attention,  although  only  individual  pumping  plants  have  been 
used  so  far. 

The  farms  are  of  medium  size,  and  a  few  are  being  subdivided. 
The  best  alluvial  lands  are  valued  at  $200  to  $500  an  acre,  the  bench 
lands  at  $75  to  $200  an  acre,  and  hill  lands  suitable  only  for  pasture 
at  $5  to  $20  an  acre.  Most  of  the  farms  are  operated  by  the  owners, 
but  a  fair  supply  of  labor  is  available  at  reasonable  prices. 

The  residual  soils  of  the  area  are  relatively  unimportant  agri- 
culturally. They  are  classed  with  the  Mariposa,  Aiken,  Olympic, 
and  Climax  series.  With  some  areas  of  Rough  mountainous  land. 

The  Mariposa  soils  are  pale  yellow  to  grayish  yellow.  This  series 
is  represented  by  a  single  type — the  loam.  It  is  of  Ioav  productive- 
ness and  is  used  for  pasture.  The  Aiken  soils  are  red.  The  loam 
and  stony  loam  are  recognized  in  this  area.  They  are  productive 
soils,  but  are  quite  limited  in  extent.  The  Olympic  soils  are  brown. 
Only  the  loam  and  the  stony  loam  of  the  series  are  mapped.  They 
occur  in  very  small  areas  and  are  used  mainly  for  pasture.  The 
Climax  soils  are  black.  The  Climax  clay  adobe  is  the  only  type  of 
this  series  encountered  in  the  area.  Many  small  areas  of  this  soil 
are  found,  and  they  are  mainly  in  pasture.  Rough  mountainous  land 
includes  most  of  the  hill  land  bordering  the  arable  valleys  on  both 
sides.  Most  of  the  hills  are  covered  wdth  residual  soils  belonging  to 
the  series  mentioned  above,  but  the  soil  is  shallow  and  subject  to 
destructive  erosion. 

Soils  derived  from  old  valley-filling  material  occupy  the  benches 
and  terraces.  They  are  classed  wdth  the  Corning,  Pleasanton.  and 
Pinole  series.  The  Corning  soils  are  pale  red,  and  the  subsoils  are 
heavier  in  texture  than  the  surface  soils.     The  loam,  the  gravelly 


SOJL    SURVEY    OF    THE    UKTAH    AREA,    CALIFORNIA.  53 

loam,  and  the  gravelly  cla_y  loam  types  are  recognized.  The  Pleas- 
anton  series  is  represented  by  a  single  member,  the  gravelly  loam. 
This  soil  is  dark  grayish  brown.  It  is  of  fair  productiveness.  The 
Pinole  soils  are  pale  yellow  to  light  yellowish  brown.  The  sandj' 
loam,  the  loam,  and  the  gravelly  loam  are  mapped  in  this  area.  The 
gravelly  loam  is  an  extensive  type  of  fair  productiveness. 

The  recent  alluvial  soils  occupy  fans  and  stream  flood  plains. 
They  are  classed  with  the  Yolo,  Tehama,  Honcut,  and  Dublin  series, 
and  the  nonagri cultural  type  Riverwash.  The  Yolo  soils  are  brown 
to  dark  brown.  The  various  types  encountered,  with  their  stream- 
bottom  phases,  are  very  productive  and  the  most  highly  prized  soils 
in  the  area.  The  Tehama  soils  are  brownish  yellow  to  grayish  yellow. 
The  loam  and  the  gravelly  loam  are  mapped,  with  inextensive  areas 
of  phases  of  the  fine  sandy  loam  and  silt  loam.  They  are  not  quite 
so  productive  as  the  Yolo  soils.  The  Honcut  soils,  as  they  occur  in 
this  survey,  are  dark  reddish  brown  to  dark  red.  Red  phases  of  two 
of  these  types  are  mapped,  the  loam  and  graAxlh^  loam.  They  occur 
in  small  areas.  The  Dublin  series  is  represented  by  the  clay  type. 
This  soil  is  black.    It  is  a  type  of  minor  importance. 

o 


'■liiiiniiMirpuSiiiMIIII 


B  IfilB  llHtl 


s 


,.  I  I  i 
1  ti  I 


[Public  Resoltttion — ^No.  9.1 

JOINT  RESOLUTION  Amendin?  public  resolution  numbered  eight,  Fifty-sixth  Congress, 
second  session,  approved  February  twenty-third,  nineteen  hundred  and  one,  "  providing 
for  the  printing  annually  of  the  report  on  field  operations  of  the  Division  of  Soils, 
Department  of  Agriculture." 

Resolved  hy  the  Senate  and  House  of  Representatives  of  the  United  States  of 
America  in  Congress  assembled,  That  public  resolution  numbered  eight,  Fifty- 
sixth  Congress,  second  session,  approved  February  twenty-third,  nineteen  hun- 
dred and  one,  be  amended  by  striking  out  all  after  the  resolving  clause  and 
inserting  in  lieu  thereof  the  following: 

That'  there  shall  be  printed  ten  thousand  five  hundred  copies  of  the  report  on 
field  operations  of  the  Division  of  Soils,  Department  of  Agriculture,  of  which 
one  thousand  five  hundred  copies  shall  be  for  the  use  of  tlie  Senate,  three  thou- 
sand copies  for  the  use  of  the  House  of  Representatives,  and  six  thousand  copies 
for  the  use  of  the  Department  of  Agriculture :  Provided,  That  in  addition  to  the 
number  of  copies  above  provided  for  there  shall  be  printed,  as  soon  as  the  manu- 
script can  be  prepared,  with  the  necessary  maps  and  illustrations  to  accompany 
it,  a  report  on  each  area  surveyed,  in  the  form  of  advance  sheets,  bound  in  paper 
covers,  of  which  five  hundred  copies  shall  be  for  the  use  of  each  Senator  from 
the  State,  two  thousand  copies  for  the  use  of  each  Representative  for  the  con- 
gressional district  or  districts  in  which  the  survey  is  made,  and  one  thousand 
copies  for  the  use  of  the  Department  of  Agriculture. 

Approved,  March  14,  1904. 

[On  July  1,  1901,  the  Division  of  Soils  was  reorganized  as  the  Bureau  of  Soils.] 


UC  SOUTHERN  REGIONAL  LIBRARY  FACILITY 


D    001  088  334    6 


RECONNOISSANCt 
AREAS 


Map  showing  areas  surveyed  in  California. 


Geology-Geophysics  Librari 
4697  Geology 
University  of  California 
Los  Angeles,  CA  90024 


